In the previous article I began the long examination of the various diseases to which are fish are prone, with a division of the ailments into the different divisions which is the methodology used in Fish Pathology. For those of you who read this column, you will recall that I began with the freshwater parasite commonly known as “white spot” or “Ick” , the scientific name being Ichthyophthirius multifiliis . This parasite was chosen, because it is probably the most ubiquitous of all the ailments that strike in fresh water Aquaria, & is common in Aquaculture as well.

Afterwards, as I began to contemplate the topics for discussion in the next version, I realized that a high percentage of you, (judging by the “hits” & the articles we have currently) are Salt water enthusiasts, so I have decided from now on, to try & balance the articles, with an examination of a fresh water and a salt water disease with each contribution.

In freshwater this month, we will examine the parasite known as Chilodonella , whilst for salt water we will look at the counterpart of Ichthyophthirius multifiliis , which is Cryptocaryon irritans . If any of you out there in the wide world of cyberspace, have any questions about the articles, or if there is a subject you would especially like me to deal with, please contact me at my E-Mail address john@aquarium-gardening.com

Chilodonella

Chilodonella cyprinii parasite under the microscope

Chilodonella cyprinii. Causative organism: Ciliated protozoan parasite viz:- Chilodonella cyprinii . Synonyms ( alternative names):- None Geographic distribution. World wide. Water type . Fresh water. Typical signs of infection. Chilodonella cyprinii.

Water. Poor water quality can bring on the reproduction of the parasite, as the fish become stressed.

Behaviour. Laboured breathing, and fish may appear at surface gasping for air. Fish will evidence lethargy, and may from time to time, try to “scratch” of the organisms, by rubbing against an object of some kind in the Aquarium. Distress is visibly obvious.

Fins. Fins often become clamped or folded

Body. Excessive mucous production is typical, & parts of the body will manifest a cloudiness as large numbers of the parasite begin feeding of the epithelial layers.

Gills. Gill examination will show large numbers of the leaf shaped organisms .

Skin. (smear). Should show ciliates once an infection has become established.

Life cycle & method of transmission.

This protozoan parasite occurs frequently in fresh water Aquaria, & has a counterpart in marine aquaria called Brookynella. The parasite is vaguely leaf shaped with a length of 40-70 microns, & a width of some 30-50 microns. The ventral side of the parasite is covered with cilia. Inside the cell for those of you, who have a microscope, & wish to examine same, are a nucleus and two contractile vacuoles. These are made more evident, by staining the slide with a smear taken from an infected fish, using a stain such as methylene blue, or methyl violet.

Reproduction of the parasite takes place typically by mitotic division, but from time to time a pairing of two individuals takes place called conjugation, and an exchange of some genetic material probably takes place.

As with many parasitic infestations, Chilodonella can lie dormant for long periods of time, but if and when the fish becomes stressed or weakened for any reason, or if the quality of the water conditions in the Aquarium deteriorate, then rapid reproduction of the parasites can ensue, and once the gills are attacked mortality is to be expected.

Prognosis

When a heavy infestation of Chilodonella has taken hold, then some casualties are to be expected. Usually certain species such as Discus, will become infected most severely first, but if untreated other varieties will succumb as well. However if correct treatment is applied in good time, then it can not only be checked but it is also possible to eliminate the parasite.

Young fish have less capacity to resist the parasite, and will more easily succumb.

Treatment

Fortunately if successfully diagnosed , there are several treatments that can be used.

These include the use of formaldehyde used as a bath, also Acriflavine type drugs, as well as with Methylene blue, also quinine type drugs, all are effective. One should follow the manufacturer’s instructions for treatment, as different producers, use different concentrations, & it is therefore impossible to give a standard treatment for all the medications out there.

In treating the fish, one should always make allowances for the degree of infection, as weakened fish may not always withstand the full dosage, either in strength, or period of time. This call is one which either one builds up experience over time, or enlists the help of a professional, or a dealer whose expertise you can trust.

As Chilodonella is not affected by change of water temperature, no alteration should be made to your thermostat.

Bibliography.

Langdon et al. 1985. Death in Australian freshwater fishes associated with Chilodonella hexasticha infection. In Australian Veterinary Journal 62, 409-413

Untergasser D. 1989. In Handbook of Fish Diseases. Publ. TFH page 95.

Van Duijn C. 1973. In Diseases of Fishes . pages 70-72.

Cryptocaryon irritans

Moderate to heavy infestation of C. irritans on Tomato Clown

Cryptocaryon irritans Causative organism: Ciliated protozoan parasite viz:- Cryptocaryon irritans Synonyms ( alternative names):- Marine white spot. Geographic distribution. World wide. Water type . Salt water. Typical signs of infection. Cryptocaryon irritans.

Water. Less than optimum water quality, such as a lowering of the pH level, or high Nitrate or Phosphate readings can lead to an outbreak.

Behaviour. Fish will evidence lethargy, and may from time to time, try to “scratch” of the organisms, by rubbing against an object of some kind in the Aquarium. Distress is visibly obvious.

Fins. Fins often become clamped or folded. White spots (after which the disease is popularly named) usually appear often at first on the pectoral fins. As infection progresses, very large numbers of these spots of size 0.5-2.0 mm will spread .

Body. White spots appear on the body, & will if untreated spread so that almost snow like appearance will spread over its entirety. Some haemorrhaging may appear in later stages of the disease.

Eyes. In medium to advanced stages of an outbreak, the eyes typically become clouded, & when very heavy blindness can ensue.

Gills. Gill examination will show large numbers of the organisms .

Skin. (smear). Should show ciliates once an infection has become established. Secondary infection with fungal is commonplace once major invasion of the skin has taken place, adding to the problem.

Life cycle

Transmission is direct, with no intermediate hosts. Cryptocaryon is an obligate parasite, which means that it must infect a host fish in order to complete development.

Life cycle of Cryptocaryon irritans. Chart by Dr.Peter Burgess.

The life cycle of Cryptocaryon can be conveniently divided into four basic stages. Susceptible marine fish become infected with the active free-swimming stage, called the theront (or tomite).

The theront is incapable of feeding within the aquatic environment and therefore has a limited time, less than 12 hours, in which to contact and invade a fish, otherwise it will exhaust its energy reserves and die. If invasion is successful, the theront penetrates below the skin epithelium, possibly aided by digestive enzymes such as hyaluronidase, and transforms into the parasitic stage which is known as a trophont. The trophont actively feeds on the fish’s tissues, twisting and rotating as it does so. It grows rapidly, doubling in size approximately every 24 hours. By 48 hours, the parasitic trophont is just visible to the naked eye, appearing as a small white spot on the fish. By the third or fourth day of infection, the trophont will have attained 3 to 5 millimetres in length and at about this time it exits from the fish. Although the trophont is equipped with rows of beating cilia it is too bulky to swim away from its host and instead it sediments to the substrate. (Compare with freshwater whitespot in which the trophont stage actively swims after leaving its host). Within a few hours, the trophont has firmly attached to the substrate and rounds up to form a thick-walled cyst. The cyst, also known as a tomont, is the reproductive stage which will eventually give rise to between 100 and 300 infective theronts, thereby completing the life cycle. Of course, not all theronts are successful in locating and infecting a host, even under ideal conditions only about 5-10% succeed. Nevertheless, within an closed environment, Cryptocaryon can increase in numbers by approximately tenfold every six to eight days. This enormous reproductive potential explains the sometimes rapid build-up of infection levels in any closed system..

The cyst is the only stage of Cryptocaryon which is known to reproduce; there is no conclusive evidence to suggest that the parasitic trophont stage can multiply within the fish’s epithelium.

Prognosis

There is no reason why mortalities should take place, as to reach lethal levels this parasite usually takes some 7-12 days. Observant hobbyists should take remedial action, at an early stage & if this is done, and the results CAREFULLY monitored than a successful eradication of the problem is possible. Care must be taken, to ensure that no latent parasitic tomonts are still present, so that the problem does not recur.

Treatment

In those Aquaria, where fish only are present, Copper based remedies, are very effective, although those chelated forms of Copper of which there are several have not in the writers experience given good results. The claim that you can use heavy doses of such Coppers, without harming the fish may be true, regretably the same argument applies to the parasite. With the true Copper treatments that are effective it is vital to use a reliable Copper test kit, & in the first few days of treatment this must be done several times daily, as the Copper in a new tank to be treated, “binds’ to the glass the rocks, and just about anything else, so that the therapeutic level drops below the recommended amount, & under this the parasite is able to complete its life cycle. Treatment should be continued for at least 7 days after all signs are absent, to ensure that no latent tomonts are waiting the chance to re-infect.

In Reef Aquaria, however no Copper treatments can be used, as they all will have fatal effects on almost all Invertebrate life. This leaves the Hobbyist with the alternative of catching his/her fish, & treating in a separate Aquarium. This is time consuming & can often ruin the appearance of a tank that has been carefully nurtured over a long period of time.

Fortunately Fish-Vet has today a product called Ecolibrium which allows successful treatment of this scourge, and is harmless to all Invertebrates. We will be pleased to advise any Hobbyist where this product can be obtained . No test kits are needed and it biodegrades after a week, after treatment has ceased.

Another technique which can be used to help accelerate the eradication of the problem, is by giving the fish baths in either fresh water, or at a salinity of less than 10 ppt. The parasite cannot tolerate the change in osmotic pressure, though I am not sure if it will affect the tomite stage as much as it will the free swimming trophont. This technique has been used very successfully in Aquaculture with those species of fish that are highly euryhaline (= able to tolerate wide variations of salinity). Our Aquarium fish for the most part will tolerate baths of up to a half an hour, but one must ensure that the pH & Temperature are similar to the Aquarium water. Also do not do any other task whilst the bath is taking place, as some fish will react more than others. If major distress is observed, the fish must be returned to the Aquarium. I have used this method to reduce the level of infection, and it has proved beneficial, though never absolute. It’s greatest advantage is when the fish shows evidence of a high level of infestation, and one wishes to bring it down somewhat before starting more conventional treatment. For more details on the use of this method see the ref. below by Colorni 1987.

There is some evidence that there are 2-3 different strains of Cryptocaryon irritans , nobody to my knowledge has yet made a definitive analysis of such, but the empirical evidence would seem to indicate this. One observation made by many observers, is that the treatment that in one case is quickly and totally successful, in another either is not, or takes much longer to have an effect. One pragmatic point that the writer has used with success is those persistent cases, that either do not appear to react to conventional treatments , or do so much more slowly, is that it seems that the parasite is in some way linked in its life cycle to the photoperiod. In order to disrupt its usual timing of division, reproduction etc, I have found it helpful on occasion to leave the lights on for some 2 days, then do the opposite whilst at the same time covering the tank with a dark blanket or suchlike. This “manipulation” of the light seems to have a deleterious effect on the parasite, which coupled with the medication used often results in its elimination. I do not advise this however in the more usual straight forward cases.

A special observation:- The writer has observed with some of his co-workers on many occasions, that Crytocaryon irritans often breaks out under the following conditions. The Hobbyist will have a tank with several specimens all of which are free of any signs of the parasite. A new fish will be introduced & the following day, “white spots” will be observed in a great many cases, NOT on the new introduction, but on one of established inhabitants. This happened so often so years ago, that we made some experiments on apparently “disease free fish”. Most especially some powder blue, & yellow Tangs.

Cyst of C.irritans

We found on these fish, which had been free of all problems for more than half a year, that when we did some skin scrapings, that we found evidence of trophonts under the skin. Evidently these had not found it necessary to reproduce & leave the fish, as no sign of disease had occurred over a long period of time

With this evidence we explained the phenomena just mentioned as follows:-

A parasite by definition has a vested interest in co-existing with it’s host. As long as no unusual disturbance takes place, it will continue it’s idyllic existence , in harmony with it’s host. However when a new specimen is introduced to the Aquarium, often the established inhabitants become quite excited, feeling that the newcomer will in some way, take their “space”, eat their food, or even team up with their favourite fish/companion. This causes some form of chemical message to course its way through the fishes system, in much the same way, as adrenalin causes us, to become excited if we get a fright or suchlike. This chemical message, in some way alerts the parasite, which in effect says to itself, “Oh boy!, maybe I should get out from here, & look for a new host”. The consequences are seen the next day, when it bores out from the host, leaving the telltale white spots.

To counteract this reaction, as much as possible, it is advised when introducing new fish to an established Aquarium, to do the following.

1) Introduce all specimens with the lighting as subdued as possible in the room, & with no lights on in the tank, continue this at least until the following day.

2) Change if possible one or two rocks, so that the existing fish are concentrating their attention on the change in the habitat they are used to, & not on the newcomer(s).

Of course it is also sensible if the Hobbyist has the facility to quarantine the new specimen, as they also can and do, introduce the parasite to the tank . This should be done if one has a separate quarantine tank, for at least a week, & preferably for 10 days.

John Shawn Prescott john@aquarium-gardening.com

Biobliography:-

Burgess, P.J. and Matthews, R.A. (1994). A standardized method for the in vivo maintenance of Cryptocaryon irritans (Ciliophora) using the grey mullet ( Chelon labrosus ) as an experimental host. Journal of Parasitology, 80, 288-292.

Burgess, P.J. and Matthews, R.A. (1994 ). Cryptocaryon irritans : (Ciliophora): photoperiod and transmission in marine fish. Journal of the Marine Biological Association, 74, 535-542.

Burgess, P.J. (1995). Marine Whitespot Disease. Freshwater and Marine Aquarium, 18 (1), 168-196.

Burgess, P.J. and Matthews, R.A. (1995). Fish host range of seven isolates of Cryptocaryon irritans (Ciliophora). Journal of Fish Biology, 46, 727-729.

Burgess, P.J. and Matthews, R.A. (1995). Cryptocaryon irritans (Ciliophora): acquired protective immunity in the thick-lipped mullet, Chelon labrosus . Fish and Shellfish Immunology, 5, 459-468.

Cheung, P.J., Nigrelli, R.F. and Ruggieri, G.D. (1979). Studies on cryptocaryoniasis in marine fish: effect of temperature and salinity on the reproductive cycle of Cryptocaryon irritans Brown, 1951. Journal of Fish Diseases, 2, 93-97.

Cheung, P.F., Nigrelli, R.F. and Ruggieri, G.D. (1981). Scanning electron microscopy on Cryptocaryon irritans Brown 1951, a parasitic ciliate in marine fishes. Journal of Aquariculture, 2, 7~72.

Colorni, A. (1987). Biology of Cryptocaryon irritans and strategies

Well finally (not before time, probably some of you would say), we will begin the long journey to examine the many ailments that fish are prone to. The lists are so extensive that sometimes one wonders how fish survive at all, given the countless “enemies” just waiting to strike them low.

Silver Dollar with a moderate to heavy infestation of I.multifiliis “Ick” Photo courtesy of Dr. Ed. Noga. NCSU.

Notwithstanding this, most fish given good husbandry and attention will thrive to be a constant pleasure to those of us, who like to replicate a small piece of nature in our own homes.

The diseases and problems that can afflict fish can be broken down into the following categories:

1. Parasitic
2. Bacteriological
3. Viral
4. Nutritional
5. Toxicological
6. Environmental
7. Other

Although we will deal with the latter two categories in later articles, in fact these are among the most challenging, and will become the topic eventually of some interesting discussions, but for now we will begin our investigation of diseases, by looking at the first major group, that is the parasitic species, that are endemic to so many of the tropical fish, which for the most part today are bred on farms.

Parasites of Fish

Freshwater

In considering these parasites, the Hobbyist should be aware that some parasites essentially need an intermediate host, in order to be able to complete their life cycle. In several cases such an intermediary is a snail, or some form of Invertebrate such as Daphnia, or other similar organisms. In such cases, by eliminating the intermediary we can bring the spread of the infestation to a halt.

In the wild probably a majority of fish are host to one or more parasites, but for reasons addressed in previous articles, they seldom become a major problem or cause of mortality. In fact there is considerable evidence that in some of the more prevalent parasites e.g. White spot (Ichthyophthirius multifiliis) that exposed fish can develop an immunity against further attack.

Whilst it most cases it is recommendable for the Hobbyist to purchase young specimens, (as they will live longer, & more easily adapt to the confines of his/her Aquarium), such specimens are also more prone to succumb to attacks by parasites as they have less size, and body weight to resist the damage that many of the parasites can so easily inflict.

Discus fish with typical early stage infection on pectoral fin of Ichthyophthirius multifiliis.

For this reason, any purchases, should be carefully inspected, to ensure that there are no “blemishes” of any kind, on the desired specimen, and the buyer should also ensure that no fish are bought from any tank in which any fish are manifesting unfavourable symptoms. Parasites once present in a tank can in so many instances spread rapidly with devastating effects, a fish that has been exposed and yet appear to be perfect, can break out within a day or so, spreading its parasites to others in your Aquarium.

For those of you that have the possibility , it is advisable to keep all newcomers in a separate quarantine tank, when first purchased. This will give you the chance to ensure that nothing untoward, will be transferred to the principle Aquarium, as it is counterproductive to try treating a fully planted and landscaped Aquarium, when disease breaks out. The period of such quarantine, bearing in mind the life cycles and latent period of so many of the potential problems should be 3 weeks. This is the period used by Government edict in Australia, which is one of the few countries so far, to require all imports of Tropical fish to be so held, in Government approved holding facilities. Such facilities are licensed and examined regularly. The limited number of approved Importers must keep accurate records, and anyone breaking the rules which are closely and continuously monitored, will have the sanction of repeal of his/her importing license effected without delay.

Therefore if you do take the prudent step to quarantine all new purchases, it is wise to make certain that they are kept for at least two weeks, if not three, before introducing them to their new home. I realize that such goes to a large extent against the “I want it now” , type of society we live in today, but the “I want a cure, that is 100% effective, works in one day or less , and causes no headaches” does not exist, so caution can pay off in spades, as they say.

It is also important to note, that parasitic infestations, often do not kill directly. However because of the damage they cause to the tissues as well as the vital organs of fish, they frequently cause secondary opportune infections of bacteria and or fungi, to invade the fish, bringing about a rapid death of the host, and often spreading the new infection throughout the Aquarium.

In order to avoid the potential spread of any infestation or infection, all nets, or utensils of any kind that may used with your fish, should be kept in a sterilizing solution between uses, and should be rinsed thoroughly before and after use.

Methods of diagnosis: (Parasites)

Although it is possible to come to a reasonable diagnosis, by carefully noting observed signs (symptoms or indications), which in fact is part of the purpose of this series of articles, it is most useful if the Aquarist can manage to have on hand the following tools to aid and help confirm their findings.

An inexpensive stereo microscope. This should have magnifications of 10-40 times to enable one to observe the majority of the parasites. Such microscopes can be bought new nowadays for around ₤250, but many are available from secondhand dealers, for about a third of this price. If buying a used instrument ensure that the optics and mechanical system are in good working order prior to commitment.

A few glass or plastic Petri dishes of suitable size in which one can lay the fish in a small amount of water whilst making observations.

A simple fine pair of tweezers, which can be used to “pick of” some of the larger parasitic forms for closer examination, without keeping the fish too long out of water.

Some glass microscope slides for making skin smears.

A simple plastic rod (thin about 3mm diameter) which can be used to gently pry open the gills of the fish for examination.

A fine pair of scissors which may be needed to excise a small piece of fin tissue, for closer examination.

A glass pipette, which may be used to aspirate (suck), some material from the gills or elsewhere for further examination.

Whilst these materials are not essential, they do make accurate diagnosis, far more certain, and any Hobbyist who has invested serious money in their Aquarium(s), would be well advised to try and obtain the above items.

Diagnostic procedures.

Whenever fish are observed with some abnormal signs or behaviour pattern, it behoves one without delay to try to make a determination of what is the cause.

Even if one suspects that the cause may be parasitical, bacterial, or viral, the first thing that should be observed and noted are ALL the water parameters. Often an adverse change in the quality of the water can induce latent potential infections to break out, so that even with a correct diagnosis it will be extremely difficult to treat the problem without taking steps to remedy the cause of the water in-balance. Some signs such as hanging at the surface, are common to the observed indications for some diseases, but also to water quality problems like Ammonia toxicity. Thus even though we will pursue all the recognized procedures for determining the cause, first ensure that the water parameters are where they should be for the species you are keeping.

Poor water quality can bring on many parasitic diseases. Reliable & easy to use test kits, like the ones by Red Sea, should be used to ensure that the quality of the water is in accordance with normal parameters.

If for any reason they are not, take the appropriate steps to rectify the problem, ensuring that any correctional changes are made slowly to avoid further stressing the fish.

Assuming the water quality is within normal values, then one should proceed as follows:-

Note down all external observations that are abnormal.

Behaviour
One should examine any signs of abnormal behaviour, such as unusual swimming patterns, refusing all food etc.

Body
Look especially for colour changes, bleeding or ulcers, swellings etc.

Skin
Try & observe any cuts or lacerations, scales protruding etc.

Eyes
Observe if any Exopthalmia (popeye) is apparent, or cloudiness etc.

Gills
Examine the Gills & note if the colour is a normal bright red, or if it shows unusual colour or other markings.

Fins
Note if the fins appear normal, or are rotting, or show markings etc.

In our Fish-Vet TM application, we have currently some 200+ abnormal indications.

When all the unusual signs have been noted it is then sometimes possible with the aid of a good text book or computer programme, to make a determination. However just as in human and animal medicine, we like to have absolute confirmation, for this reason some of the verifications which follow should be attempted, this assuming you have the above mentioned equipment. If one does not, then the specific details of each disease, should be kept, as a reference source, along with any other good book that one has, as you make your best shot, at the problem, without the “proofs” which we will now talk about.

Skin smears. Probably the easiest and often the one that will “prove” the diagnosis fastest and most conclusively at least as far as parasitic infections are concerned is the skin smear. In order to do this one takes a clean microscope slide and simply presses it gently over the area on the fish that one suspects is a source of the problem. One can also “run” the edge of the slide along the infected area, with a little pressure, this will almost always release some of the epithelial matter along with some indication in many cases of the causative organism.

A word of caution. In a fish that may have had a wound or similar for quite some time, ( over a couple of days), there may already be secondary infections taking place, of a fungal &/or bacterial nature, it is important to be aware of this when taking such a smear, so these are best done in the earliest stages for best results.

Once the smear has been made, it should have a drop of clean water should be added to the slide with a pipette, an examination under the microscope should then take place. Be careful when adding the drop of water that only a small amount is added, otherwise the vital material to be examined can all to easily “flow” off the slide making the examination more difficult or useless.

Again a good reference book, or computer programme will be needed for most Hobbyists to enable them to recognize the causative organism which may then be observed.

Fin Biopsy. If the fins show any abnormality, one should take the fish, holding it gently but firmly in a wet clean net, and using a fine pair of scissors, cut a small piece of tissue from a fin that is showing signs of abnormality. Cut between the fin rays, so that only tissue is removed, in this way minimal damage to the fish will ensue. Proceed to examine the sample in the same way as with skin smears.

Gill examination Hold the fish as mentioned above, prise open the gill covers with the mentioned clean plastic rod. Insert a fine pipette & aspirate (suck) a small amount of tissue, from the gill lamellae taking from any part that may appear abnormal ( dark in colour, pale, with small black or white dots etc). Let this material drop onto a clean slide as before then proceed to examine same.

Wet mount of a Gill Biopsy showing I.mutifiliis trophozoites. Photo courtesy of Dr. Ed. Noga. NCSU.

Should one need to proceed to do post mortem examination of a dead fish, then it is advisable to use a qualified laboratory, to take samples from some of the internal organs as well as the outer body. For such examinations detailed methodology which requires some special preservatives, as well as certain specimen holders and more must be used, otherwise the chances of it arriving in a fish disease laboratory in a useable form are remote. Laboratories tell us that nearly half the samples they receive cannot be used as they have not been prepared correctly. Qualified laboratories will instruct persons what procedures must be followed.

Armed with your notes on external signs & adding to this confirmatory examinations as indicated it should be possible to make accurate determinations for at least the majority of parasitic infections.

We will now deal with the major parasitic species as our typically found in the Aquarium, beginning with by far the most prevalent.

White spot (Ichthyophthirius multifiliis)

Causative organism
Ciliated parasite viz:- Ichthyophthirius multifiliis with a complex life cycle.
Synonyms ( alternative names)
White spot, or “Ick”.
Geographic distribution
World wide.
Water type
Fresh & Brackish water. ( similar organism Cryptocaryon irritans is a salt water parasite.)
Trophont stage of Ichthyophthirius multifiliis “Ick”. Note the typical ‘u’ shaped nucleus.

Typical signs of infection. Ichthyophthirius multifiliis aka “Ick”.

Water. Elevated Ammonia levels, high Nitrate measurements, sudden changes in Temperature especially a fall in Temperature cam bring about a latent infection.

Behaviour. Anorexia, (loss of appetite with consequential wasting), hiding abnormally, rubbing and scratching , breathing at the surface, fast respiration, refusing all food are all typical indications, but these are also signs in other problems so diagnosis must be coupled with other indications.

Fins. Fins folded, Fins showing white spots about 1mm in size.

Body. White spots from 0 . 2mm - 1mm in size will appear over the body.

Eyes. Eyes may appear cloudy.

Gills. Gill examination may show numbers of such white spots.

Skin. (smear). Should show ciliates if white spot is present.

Black Widow showing typical “Ick” sign, of a folded dorsal fin, this sign often appears in the early stages.

Life cycle & method of transmission.

White spot, is a parasite that covers the entire globe, there are few Aquarists that have not met it on one or more occasions. A sudden chilling of the fish, which can easily occur when they are being transported from the shop to one’s home, is often sufficient to take the parasite from its latent state to the reproductive phase. An unchecked outbreak will bring about a heavy mortality rate, though it takes usually quite a number of days before such comes to pass, thus giving the Aquarist time to take remedial action.

White spot “Ich”, is a ciliated parasite with a three stage life cycle. On the fish, the only part that we can easily observe, the form is termed a trophont , & causes the appearance that gives rise to the popular name of the condition, i.e. “White spot” As the trophont matures it eventually breaks through the skin ( epithelial layer), then falls to the bottom of the tank, during which phase it can attach itself to any of the various materials that we use in our Aquaria, such as gravel, filters, airline tubing and more.

Theronts leaving the cyst (Tomont stage). Ichthyophthirius multifiliis.

This part of the life cycle is called a tomont. How long it remains in this stage is a variable as a higher temperature will accelerate its maturation, whilst colder water ensure a longer latency. For this reason many Aquarists use an elevated temperature to try & cause the parasite to mutate into the final re-infective form termed a theront.

The parasite is at its most vulnerable whilst in the free swimming Trophont form before it encysts as a Tomont. Various chemical therapies are effective, such as Malachite green, or Malachite green with formaldehyde. The Theront stage is very sensitive to higher temperatures, which is the reason that many skilled Aquarists often try eliminating an outbreak, purely by increasing the number of degrees Centigrade by some 3-5 ° whilst the infestation is endemic.

Prognosis :

If diagnosed early & effectual treatment is applied, the outlook is excellent. However if the infestation is at an advanced stage, then mortalities must be expected. Any treatment method must take into account, both the species of fish ( some will not tolerate the more popular medications , see below), as well as how heavy the infection rate is. Diligent observation of these criteria should enable the Aquarist to obtain a successful resolution to the problem.

Treatment
Most proprietary medications give the recommended dosage, but there are several cautions which must be noted, when using any of the mentioned treatment methods.
The popular treatments contain Malachite green, sometimes combined with Formalin.
The dosage will vary according to the manufacturer, but a typical treatment level for Malachite green is .1mg/L of water. Formalin ranges form .25mg/L to much higher levels depending on the combination with Malachite green or it’s usage alone, also on whether it is meant as a timed bath treatment of prolonged immersion. One must refer to the instructions on the chosen medication but also be aware of the points below to achieve the desired result.

1) The species of fish. Some fish especially scaleless forms such as Clown Loach, Elephant noses, plus many others, as well as a great many Tetras, are adversely impacted by the use of Malachite green, or some cannot tolerate the full dosage that others can. It is therefore essential, that before applying any chemotherapy , that one is aware of the limitations of the chosen treatment, if in doubt seek some professional advice. Otherwise the “cure” could be worse than the disease. I have seen many times, entire tanks of fish wiped out for this reason, sick and healthy fish alike.

2) Heat treatment, which can be highly effective. However again there are species of fish, that will not tolerate the temperatures needed to be effective. One such example would be White Cloud Mountain Minnows. A temperature of say 22c or higher, will cause such fish to succumb very quickly.

3) The degree of the infection. Grossly weakened fish, will not tolerate medication that more robust and less infected ones may. All medications to some degree, are toxic not only to the parasite but also to the fish, it is a matter of judgment, that can take many years of experience to know just how much of a medication to use. The guide lines given on most proprietary treatments, can only be considered guidelines, so the user must take into account the many variables before making his/her call on how much to use.

It is also vital to ensure that after a treatment has been selected & found efficacious to make certain that water changes are made afterwards to try to minimize any side effects on bacteriological filters as well as plants etc. Naturally if it is possible, it is better to treat in a hospital tank, and when the fish are cured to reintroduce them to the main Aquarium. This ideal situation is not always possible however.

A treatment that I have found effective but not one that all readers will find practical, is to place infected fish in a small 10 Gal. Aquarium with some outside filtration. There should be no rocks or other ornaments for the Trophont’s to adhere to easily. Another one or two such Aquaria are also set up, and the water in each must match in every parameter (Temp. pH, alkalinity etc.) the original tank water. About every eight hours the fish are transferred to a “clean” tank, thus breaking the possibility of the parasite obtaining a new host. The emptied tank is then sterilized & refilled with water, again paying close attention to the water parameters as before. If this procedure can be carried out by the Aquarist, it will usually result in a cure within a matter of some 3-4 days, though caution should be employed for another day or so, to ensure all is in order, before putting the fish back to the main tank. Although time & space consuming, it has the advantage, that no chemicals need to used, so consequently the fish are far less stressed, even allowing for the trauma of moving them. The treatment tanks should be in a quiet place, as there is no place for the fish to hide, they are in this way not “excited” as this would be counterproductive. Of course small tanks like this will not work for large fish, such a grown Oscars and many others, but it is a technique well worth considering.

Refs. & further reading.
C.van Duijn Diseases of Fish . Published by Ilife books London. 1973
M.Stoskopf. Fish Medicine . Published by W.B. Saunders. 1993
D.Untergasser. Fish diseases. Published by TFH. 1989

Readers will recall that in the last two articles, I attempted to show the important contrasts in stress, and therefore the potential for disease between fish as they are in Nature, & those that are kept in captivity, especially those that are kept in Aquariums.

Today throughout the world, fish are been bred in captivity for food in most cases, but also for our Hobby. It is a fact that today, a very large percentage of the fish we enjoy watching in our home Aquaria, have been bred in captivity. This is a far cry, from the early days of the Hobby, when almost 100% of the fish which were sold, came from wild caught supplies, in many countries.

Although there are similarities, between the environments in which Aquaculture maintains and breeds its fish, to those we create for the home aquarium, there are also important differences. In order to better understand, how fish may be stressed & become ill, it is useful to be able to make such comparisons, which are set forth in Table 1. Below:-

I think it is informative, to look carefully at this short list, as it makes us focus on, what are the similarities, and even more importantly the differences which occur. I maintain that these differences account in quite some measure for the diseases, including the factors that induce our fish to become sick, in too many instances.

Diversity.

We see that in the rivers and oceans, that fish are present, in great numbers as well as in many species. Although predation is natural , the various species have evolved methods to deal with it, such as camouflage , shoaling, natural habitats which give shelter, to name only a few, therefore the fish does not feel stressed, as part of its existence, unless exceptional conditions arise.

In Aquaculture fish are raised in a number of different ways. These include earthen ponds, cages, raceways, ( of many types of construction), sea cages in open sea, and protected bays, as well as entrapped bodies of water, Streams, and Lakes, as well as several other variations of these. For the most part in Aquaculture the fish are the same species, though there is a trend in some areas to Polyculture, ( the rearing of two or more species, which are compatible, in the same environment). Here at least although stress can and does arise for other reasons, the stress that can be caused by an incorrect choice of species in the Aquarium does not arise.

In Aquariums, it is usual to find a few too many kinds of fish, the discerning Aquarist, will ensure their compatibility, but often by wrong advice or being unaware he will put a fish or two, into the Aquarium, which will become very aggressive to others, such can and will cause stress to other fish, which can quickly result in disease breaking out.

Density.

In Nature, the oceans are to a large extent unlimited at least as far as the numbers of fish are concerned. Thus although the numbers in some shoals may be enormous, there is never any problem of overcrowding or the consequential deterioration of the water quality.

In Aquaculture, the name of the game, is to get the absolute maximum numbers of fish, per given size of tank, cage , pond or whatever, as is commensurate with rearing the fish to point of sale, without them getting ill. The expert fish farmers, spends much of their effort, in trying to achieve just this. However from time to time for many different reasons, engineering breakdown, storms, changes in water quality, the fish may be and are sometimes subjected to tremendous stress, so when this happens, the window of time to rectify this is short, and often very limited.

In Aquaria, except with those novice Aquarists, whose enthusiasm exceeds their current knowledge, today most Aquariums, are not overcrowded. When this rule of giving reasonable space to the species we intend to keep, & ensuring that we have made due allowance for the eventual size they will become, the question of density causing stress should not be a factor. Remember though, especially newcomers to the Hobby, it can easily become a factor. Thus choose your fish thoughtfully, & with careful research into the compatibility with the fish you already have.

Water quality.

In Nature the water quality is for the most part a constant, with a few exceptional conditions, which may be caused by run off, or flooding etc. Here the fish has evolved in its ideal habitat, & it is very rare, for any stress to be caused by water chemistry, or temperature changes, other than those which are natural. However increasingly & most regrettably, there is yearly more reported “Red Tides” and similar type occurrences, which are not fully understood at this time by Science. Much informed opinion leans towards the explanation, in at least a large number of cases, that mankind’s alteration of the environment by run-off’s , by untreated sewerage, by oil spills, by damming of rivers, plus so much more. These “Red Tides”, are in many cases, highly lethal, sometimes to the fish themselves, other times to humans who may ingest species exposed to these tides, which often cause toxins of rare potency to be formed.

In Aquaculture, water quality, in many cases, is totally controlled by the farmer.

Photo above by courtesy of Mote Marine Laboratories Sarasota Florida.

The economic losses, due to the shut downs of collection especially shellfish, during these outbreaks, by Governments, to protect public health, runs into millions of dollars, so assuming that we as humans are in some measure responsible, the consequential losses in economic terms are considerable.

Authors note:- When the advocates of easier (read uncontrolled) development push for less Government regulation, in almost every case to make their development plans proceed without the checks & balances that mankind has attempted to put in place this century, they always understandably look at their own projected bottom line. I believe that as we now have crossed that famous “bridge to the 21st century, that a new form of accounting must urgently be introduced into top decision and Nations law making. We need to look at a much wider picture, to see the broader costs to all of us. Furthermore I feel a property tax on business that would take into account all forms of pollution, discharges of all kinds, as well perhaps of aesthetics, so that the largest polluters paid the highest tax. This would give the correct incentives to the heaviest polluters to take remedial action. Furthermore it would increase the already thriving industry, that produce all forms of pollution control machinery & equipment. At the end of the day, such polluters, would obviously pass on to us the consumers the costs, but all of us would be paying the cost of pollution, and not just an unfortunate few. Competition moreover, would quickly reassert itself , so that those companies that did not “move with the times” would soon find themselves, in an uncompetitive position. Thus we could attack pollution while still retaining the profit motive.

Oyster Farming in the Orient is very productive, but massive excretions can cause major changes in water quality.

In Aquaculture, the water quality, is in many cases, totally controlled by the farmer, although in sea cages, it can be similar to nature, though even here some problems have arisen. Because this vital parameter is so important, in most fish farms, water changing is a part of the everyday routine. Not withstanding this, many are the occasions when some vital chemical or other parameter, will change, almost invariably for the worse, and this can threaten the stock of the farm, often within a horrifically short period of time, which can amount to less than an hour in extreme cases.

In Aquariums we today have the technology to control water quality to a high degree. Notwithstanding this, for a large number of good reasons, the water quality from Aquarist to Aquarist, varies in large degree, form superb, to abysmal . Among the myriad of reasons, are, lack of good advice from the dealer, lack of adequate funds to purchase some of the essential equipment, poor water quality at source, & there are several others. The high quality Aquaria, will encounter a much lower level of diseases, whilst one can be sure, that the lower levels of water quality, will have the highest incidence of disease outbreaks. One can also say with certainty that many of the Aquarists who quit the Hobby, do so because they have lost too many fish due to disease. It will help everyone to be successful, if we can try together to reduce disease, & improve where necessary the water quality.

Good husbandry.

In Nature, this matter is not relevant, as the quality of the fishes life is natural, & it will normally thrive.

In Aquaculture, this is the essence of what fish farming is all about, & woe betide those farmers, that become careless, or do not keep up with the most successful techniques. Any improvements in technology rapidly spread in today’s world, and are quickly are reflected in the final price of the fish. For this reason most fish farmers, are constantly tending their stock and pay great attention to their well being.

In Aquariums, this is certainly also true for the elite among our Aquarists. I would say, even the majority among those of you reading this article. Regrettably this is not always the case among too many of the millions of Hobbyists out there. Lack of time, paucity of knowledge, combined with the fact that for too many, Aquarium keeping has and always will be, a passing fancy, to go along with other whims, like roller skating, baseball, the latest movie, etc. It is here that the quality of the water tends to vary downwards, with all the attendant consequences of disease, leading to final abandonment by the enthusiast for the Hobby he ardently espoused for a few weeks or months.

Predation.

In Nature, fish are constantly predating on other fish, or plankton, algae or whatever. This is part of the natural cycle of life. They in turn, with a few exceptions like large whales & sharks, are also subject to predation. Most fish have a built-in awareness of the dangers, & over eons of time, have evolved techniques to lessen the risk. Among these are shoaling (safety in numbers). Background camouflage, habitat security, development of toxins to ward of predators, association with other species, that lessens their risk, & more.

Because all of this has happened naturally, they are seldom in a heightened state of stress, although they have this consciousness that causes them to take cover, when they think danger may approach. We have all seen shoals of fish, move in sudden uniform fashion, to another direction, which is almost always, an instinctive reaction to a perceived danger, which they hope to avoid. By and large then, stress with its consequential increase in disease factor, is not very high in the natural environment.

Aquaculture, for the most part, with good management, is seldom subject to predation, unless in the case of ponds or lakes, etc., there are natural predators that may prey upon the stock. These can & sometimes are a serious nuisance. Among the worst offenders, are Herons, Pelicans, Snakes, Otters, Monitor Lizards, plus others. However any serious fish farmer, is aware of these risks, & technology today, is capable in large part of finding answers to this problem.

Sea Lice are attracted in vast numbers to the culture of Salmon in cages.

There are still some types of predation that we need to find answers to, these are the subject of constant ongoing investigations. One such in Aquaculture especially in Salmon culture is a form of predation that is in reality a parasitic disease. Sea Lice, have emerged as a substantial predator on stocks of salmon, which are now farmed in many countries of the world. These cause enormous economic damage, although some progress has been made to control them, it is not yet adequate.

In Aquariums, predation is often caused by the Aquarist being unaware of the incompatibility of the specimens he has chosen. In Reef tanks many Invertebrates, even though sessile, are capable of causing injury leading to death, of another species, when they are placed to close together so that they touch. Many species of fish will attack another kind, often incessantly, and with some major beautiful species of Angelfish. This is especially so, when the fish are the same kind and of similar size. Other species like Butterfly fishes will live on their natural food, i.e. certain corals, to the horror of the owner, who has spent hard earned money to acquire a prized specimen.

Not only does this cause losses, but the fish which are attacked rapidly develop major stress symptoms, as they (unlike in Nature) cannot escape the problem, being confined in an Aquarium. These symptoms are too often the reason that a disease will break out, which then quickly passes, to others in the tank, who although not being attacked cannot escape the spread of the infective organism(s), that ensue.

It is therefore vital that when we select species of fish or invertebrates for our Aquarium, we should ensure that we carefully taken note of what is compatible, not only with the new species we are about to buy, but also with those we already have in our tank.

Natural food.

In Nature, there is only natural food, so this is hardly ever a cause of disease, as each species seeks out the forms of nourishment most suited to its requirements. There is today an increasing danger however that as mankind has “successfully” over fished almost all of the major commercial species, that the “natural” chain of food, now for the first time, having its knock-on effect, may cause some changes in the ability of many species to have an adequate diet. This over fishing effect has already had undesirable results, with much bird life, when their preferred food species has been tremendously diminished , e.g. sand eels on the Puffin population.

The environmentalists, must also be allowed to make their studies and inputs into the decisions about fishing quotas, so we have a long way to go, before we can safely say we understand it all.

In Canada, the economy of the State of Newfoundland, was seriously impacted when the Government having for years got their statistics wrong, were forced to close down the major fishing grounds on the St. George’s bank, with the loss of some 30,000 land based and seafaring jobs. This economic loss is still affecting the local economy.

In Aquaculture, natural food is seldom applied. Almost all diets, although invariably containing some fish meal ( a major limitation at the moment on the unbridled expansion of fish farming), are produced in factories that make up a balanced feed, that contains state of the art, know-how about the various requirements of the fishes dietary needs. An interesting but minor exception to this was recently revealed on one of the bulletin boards of the Aquaculture industry. in Ireland, but they found that they were getting a very high conversion ratio, ( less than 1:1, this means that they were getting more food in production of the salmon, than they were feeding to them, on the face of it impossible). On investigation they found that the droppings from the fish were causing a “bloom” of phytoplankton, which attracted vast quantities of mysid shrimp. The salmon fed on these shrimps, & grew at a much higher rate than had ever been observed for the applied ration of food. I feel sure that variations of this may become a part of future fish farming.

There also has been in Aquaculture, because of the nature of the food, some important and costly disease/problems, among them it has been found, that some manufacturers, did not have adequate quantities of Zinc, in their diets. This caused blindness with important losses, until rectified. Other diets have been found to lack on or more of the various vitamins, or amino acids, most of which are as vital to the healthy growth of fish, as they are to all other types of living creatures. It is seldom practical to feed natural live foods to the fish in Aquaculture, but it may be pleasing to you as Aquarists to note, that when there are exceptions, it is usually from the ornamental side of the industry, that such are used. Of course in the early larval stages of Aquaculture natural live foods are used all the time, most especially in the form of Brine shrimp( Artemia), without which there would be no Aquaculture for many important species.

Aquarium use of live food is highly variable. Most good shops carry one or more varieties of live foods, a large number of serious Aquarists buy such on a regular basis, others, culture or collect their own. The use of such foods is important, in some cases vital, as there are fish, who will never touch a prepared food, such as leaf fish in Freshwater, Seahorses, Lion fish in Saltwater as well as many others.

Without such additions to their diet, many fish will progressively weaken and become prone to disease. This can be avoided, by choosing a suitable live food, feeding it regularly, though it is sometimes difficult to ensure without a great deal of trouble, that the fish that need the live fish most, get to it. Too often other faster fish, have eaten all or most of it, while slow moving fish like those mentioned, have had almost none of the same.

Another alternative is either to avoid such obligate live feed species altogether, or keep such fish species altogether, or keep such fish species in a tank to themselves. Sometimes Hobbyists will do this, while ensuring that a number of pregnant female Guppies are always present. Such females will eat almost any food, whilst the continuous supply of their offspring will provide a constant live food diet to those that will eat nothing else. Hobbyists should be aware, that Guppies, can be kept in full saltwater, and will even breed, if the “change over” is done gradually over a few days. Whilst large Lion fish, will also eat the parent stock, Seahorses will not look at an adult female, but will eat newly born fry.

Aquarists, should take careful stock of their fish, along with the eating habits of same, to ensure that the diet, is adequate and balanced, otherwise over a period, stress will develop, along with it diseases that can affect all the fish in the tank.

Water changed often

Finally in Nature the water is constantly changing, and only as said earlier if pollution occurs is their any problem on this account.

In Aquaculture water is often changed on a regular basis, or if in cages in the ocean, is subject to constant change. Notwithstanding this, from time to time even in the sea, the sheer volume of fish in a given area, has caused some massive problems, this in various ways. Good fish farmers, are aware of this problem, so today techniques to measure and control the problem are in place in the more important aquaculture countries.

In Aquariums this is a major variable. Most Aquarists are aware they should change the water on a regular basis. For reasons of time, money, “theories” that contradict the popular wisdom, as well as the insistent adverts, of some producers of additives, many change rarely or insufficiently. Without doubt, this factor is responsible for many unexplained “sudden” outbreaks of disease, in tanks that had apparently had no problems. A good rule of thumb, in Aquariums that are NOT overcrowded, is to change about 7-10% of the water volume weekly. This in both fresh or salt water tanks.

These then are the major differences between the environmental pressures that fish are subjected to, in the 3 different ways of their existence. By looking carefully at these, understanding, what helps, what does not, then by applying these principles to our Aquaria, I believe major benefits can result.

In the first article, I attempted to contrast the major differences between fish that live in a “natural state” and those kept by man, either in Aquariums, or in Aquacultural situations.

It appears that at least one person, felt somehow that I was in some way against keeping fish for pleasure, and in case there are others who might have felt likewise, I should take this opportunity to say unequivocally, that I have enjoyed keeping Aquarium fish, for well over half a century, and took up what is now my profession, because of my abiding interest in them, and which has thankfully never waned.

Queen Angels of similar size will be stressed if more then one is kept.

They may even fight to the death.

It is essential in my view to understand the “norms” of fish in the wild, as a precursor, to being able to be take the required steps to minimize the problems of disease that so often break out when fish are kept by man, in Aquariums or otherwise.

Later on in this series, I will deal with the specifics of disease, but before doing so, I would like to point out some of the similarities, as well as the major differences, between fish as kept in Aquaculture, and those which we keep in the Aquarium. This with especial regard to the influence the differences have upon disease for us Hobbyists.

In Aquaculture it is normal to rear just one species in raceways, cages or tanks. Occasionally farmers practice Polyculture ( the keeping of 2 or more species side by side), but this is not common, even when it is the practice, it is seldom more than 2 species.

It is a rare Aquarist that keeps only one or two species, in his or her Aquarium.

For the Aquaculturist, this means of course he has a much higher risk if disease should break out, as many pathogens, whether parasitical or bacterial in Nature, often have a preference for a species, which can under circumstances which are favourable then spread very quickly. Contrarily the Aquarium usually has many species which mean that some diseases at least will not spread as fast, and give the Aquarist a chance to get the problem under control.

Because of the enhanced risk, good Aquaculture practice, require the fish farmer, to pay constant attention to water quality, disinfection procedures, and the continuous observation of his stock, as any lapse can bring about serious losses, which after all are his livelihood. For this good reason today more and more farms are employing trained Biologists to manage the farms, and try to keep the risk of disease under control.

Today many more Aquarists, also pay close attention, but as it is a Hobby and not a source of revenue, for nearly all of us, the degree of close observation as well as the amount of control equipment is often much less than on a professional farm.

Another difference in many but not all farms, is that in cage culture, or such things as Trout culture, in some areas, the water body is constantly changing, taking away pollution, and renewing the quality of the water. There are of course farms that work on closed systems, but even here it is typical to make up some 2% or more of new water daily. This prevents the accumulation of undesirable “metabolites” which are most often Nitrates, Phosphates, Proteins, and more. This cleansing of the water body in Aquaculture is vital, as any diminution of the water quality, can very quickly give rise to stress, which can quickly help bring latent parasites, viruses, or bacteria, into a chronic state of infection.

Many Aquarists do of course also change water, many do not do so, or if they do it is infrequent, and anyway, even the best of us, do not do so daily. This means that we must rely on more sophisticated control methods, such as Protein skimmers, Ozone generators, UV purification, Biofilters, and much more in the form of water additives etc. For those of you who have taken the trouble to understand the reasons for such technology, and can measure the effects, this can and does yield some excellent results, such as wonderful Reef Aquariums, as well as beautiful planted fresh water Aquariums.

Regretfully, poor advice, sometimes at the dealer level, lack of time, or inadequate understanding of the often quite complex interactions, can lead to heavy losses of fish, and too often to the “retirement” of otherwise keen Hobbyists, who feel that our pastime is too difficult.

The purpose of my articles is to try in some small way, to show that this need not be so.

You have already heard me refer to stress several times as possibly the single greatest cause of fish developing disease, & before proceeding to the more specific details of disease, I would like to give a real example of something that I did with my team some years ago in the UK, which I think emphasizes this point very well.

At that time I had an Aquaculture consultancy business in the UK, but also ran our own Labs, and had adjacent to the premises a fairly large Aquarium store.

We observed the following phenomena, many times over. Typically we would receive our shipments of fish on a Thursday, so that we would be well stocked for the heavy weekend trade. We had several beautiful show tanks from which we normally never sold, & whenever we got an especially nice specimen, or something that was different we would place this fish in one of the show tanks as an attraction. I would point out that these tanks were set up for long periods of time, were maintained as professionally as possible, as they were our “Advertisement” tanks, and we often did not add a fish for several weeks.

I would mention that I am talking about Marines in the example which follows.

We made the observation that the following day after adding the “new” fish, that one or more of the “old” fish would have broken out with signs of “white spot” Cryptocaryon irritans, whilst the newly introduced fish was quite all right, showing no signs of any problem. This was contrary at that time to what we somehow expected. Also it occurred so often, that we began to develop a new theory at that time as to the cause.

In our Lab, we proceeded to do skin scrapings of the unfortunate fish, and very quickly we found encysted spores of the parasite which were obviously lying dormant and doing no harm. It should be noted that by definition a parasite has a vested interest in its hosts well being, as any change in that status, which may affect the fish, can also have undesirable effects on the parasite.

Having proven to our satisfaction the almost ubiquitous presence of this common parasite, we then proceeded to rationalize the outbreaks I referred to as follows:-

Fish as most Aquarists have observed are very territorial, they also quickly get to know an Aquarium, and also the other inhabitants, many species will stake out a place of their own, especially Clown fish andother Damsels, but also many others. When a new specimen is introduced, many fish become agitated, they feel that the newcomer, will take their favourite spot in the tank, compete for available food, or “steal away” perhaps their friends.

Such alarm can often be seen in school if we can recall when a new and challenging new face appears, especially if he or she is handsome, strong, aggressive, or clever.

Porkfish are happiest and with the least stress when they can school together.

We manifest this emotion sometimes by feelings of jealousy, or counter aggression, or displays of bravado, which may not even be natural to us. Should there be a major challenge such as occurs many times, when a bully appears, adrenaline courses through our bodies to help us cope with the stress.

My team and I, became convinced that something very similar was happening when we introduced the new fish, to those who had “rights of occupation”. Some form of chemical messenger undoubtedly ran through the veins of the resident fish, and this would “wake up” the dormant parasite who would translate this message in such a manner as to say to itself, that perhaps my host will not be around much longer, something is the matter, and this stress messenger would cause the parasite to immediately go into the reproductive phase and burrow out of the epidermal wall of the resident fish, giving rise to the typical “white spot” markings.

Although such a theory is hard to prove, pragmatically we were able to almost do so, as once armed with this conception, we always added the new fish afterwards in subdued light after having changed a couple of hours before some of the rocks in the tanks and other such position markers. We also left the lights out with the tank covered for a day or so. We did not eliminate the problem, but the number of times it happened afterwards was a small fraction of what had been an almost invariable occurrence before our experiment.

The lesson to be learned is that many things can cause stress, and that we should always seek to lessen this by understanding the underlying reason, and that if we do, we can greatly minimize the problems that all to often occur.

Therefore I hope you will bear with me when as I proceed in this series, you will find I will return frequently to the matter of good husbandry, which is effect the practice of avoidance of stress, as far as the art of Aquarium keeping allows.

Some rules which are worth repeating for those who may not know, or have perhaps forgotten or become careless, all of which will reduce stress & therefore the eventual possibility of disease.

1. When buying fish from your local dealer, try & ensure that the specimen you select, has been in his establishment for a least a week, & see it is feeding. Perhaps pay a deposit on the understanding you may change to another fish, should it not have been there long enough, assuming you really want it. The ask the dealer to keep it a few more days, & ensure you may chose another fish if it does not “measure up” Most good dealers will assist as they want you as a customer.
2. When taking a fish home, ensure that the clear plastic bag is covered by an opaque cover of some kind. Nothing will scare a fish more than being trapped in a clear bag, from which it cannot escape, & seeing all the strange sights to which it is then subject.
3. Ensure that you equalize the water temperature, as well any pH differences slowly, over at least half an hour, by the slow addition to the bag of the tank water, & floating the bag first to balance the temperatures.
4. Add the fish in as subdued a light as possible, and do not turn on the lights for the rest of the day, to view the fish, which although a natural inclination, should be resisted in the interest of longevity for your new fish, and even the old ones.
5. Ensure in both fresh & salt tanks, large numbers of hiding places, so that the fish can find a new “home” and feel secure from any perceived enemies.
6. Avoid tapping the glass, to try & bring the newcomer out from any hiding place, when it has adjusted it will display itself to your content.
7. Ensure if necessary with the advice from your dealer, if the new specimen(s) you are considering, are compatible with those you already have. Some fish are naturally antagonistic to others, whilst in Salt water, two similarly sized Angelfish of the same species will often fight to the death.
8. Do not overstock the holding capacity of your tank, crowding will induce stress very frequently, & can cause a total wipe out in some circumstances.
9. If you have burrowing fishes, such as Kuhli loach in fresh water, wrasses or some gobies in salt, ensure that the type of gravel you are using is suitable, as some are sharp & can quickly cause abrasions which will lead rapidly to the demise of the fish, & perhaps spread to others.
10. Avoid putting on lights in a darkened room, suddenly, as this unnatural shock can cause many fishes to jump out of the tanks, Swordtails are great at doing this. Either only illuminate from a room which is already lit, and if you can try to attach to your lighting system some form of Rheostat control which will bring the lights on and off slowly, just as the sun comes up and goes down in nature.

The practice of these basic rules, and no doubt others, will help towards the goal of keeping fish more in harmony, with the natural condition, and this is one as I pointed out last month, that has less virulent diseases, that can occur in Aquaculture and the Aquarium for the reasons I gave.

In the next article I will begin the process of looking at the various ways that disease can manifest itself, and begin the long process of trying to understand the many potential problems, and how we can address at least some of them.

Fish in the environment, stress, & more.

This column, which I hope to be a regular fixture, in this new and most exciting of mediums, will try and concentrate on the practical considerations relating to the health of your fish, in the real world of aquarium keeping.

Although one may think otherwise, the problems that we face as aquarists, are not exactly the same, as similar fish will face in their natural habitat, although the actual parasites, bacteria, etc. will in so many cases be those, that do sometimes create problems in the wild. Read the rest of this entry »

To be Announced.

We will be running a competition shortly, details to follow. Hint, It will involve aquariums, plants and cameras.

Please check back soon for further details.