By John Shawn Prescott

Butterfly fish showing typical early Vibrio lesion

. In this article I wish to deal with a disease which while quite prevalent in Tropical fish, is not so well known or referred to as often as it should be, in the literature. This bacterial disease goes by the name of Vibriosis The infective organism can be one of a number of varieties of this all to prevalent organism.

Vibrio bacteria are gram negative rods, which are about 0.5 X 1.5 um and are motile. When grown on suitable media they give rise to creamy coloured shiny colonies.

Possibly the most well known form is Vibrio anguillarum , called after the eels which were probably the first species to be identified in culture as been prone to infection by the pathogen.

However many other forms of the pathogen are now recorded, among them being Vibrio haemoliticus , Vibrio alginolyticus as well as others. They typically infect many forms of Marine Tropicals, but outbreaks have been reported also in some fresh water species.

Large ulcerative lesion caused by V.anguillarum

Once this pathogen is established it is very hard indeed to eradicate from a tank, without drastic measures such as pulling down the entire tank and sterilizing everything in it. This of course is not what most Hobbyists want to hear or do, but the unpleasant fact remains it is a most persistent bacteria, and can cause heavy mortality if not brought under control.

The infection has been observed in a great variety of fishes, from Damsel species, to Marine Angels, many soldier fish, squirrel fish, as well as lots of other species.

There are few infections more certain to spread to other fish in the tank, and with such virulence. Casualties are to be anticipated, and remedial action must be instituted at a very early stage, if the pathogen is to be arrested in it’s march of destruction. Although like all diseases, as I have constantly in these articles pointed out, Vibrio will be most destructive in poor environmental conditions; this pathogen can however also break out by the introduction of a fish carrying the pathogen even when the tank is in an ideal condition. For this reason no suspect fish, no matter how attractive, should ever be purchased in the hope that it will get better.

It is possible, that the outbreaks are caused by the pathogen acting as an opportunistic organism, and entering the fish, when some small but otherwise harmless breakage in the skin or another part of the anatomy, presents a suitable chance for the bacteria to multiply. This is still not sufficiently understood, but many observations would appear to indicate this.

As very few Aquarists will discover this pathogen before the disease signs manifest themselves, it is usually the case, that the pathogen will have potentially spread to other fish in the Aquarium.

Thus one should be prepared to accept that some casualties will occur, and the success of any remedial treatment will be measured therefore by the extent to which the spread of the infection can be brought under control.

Tetracycline The dosage will vary according to the chosen method.

A) 4 day bath. Use 1 gram in 100 litres of Aquarium water.

B) 24 hour bath in a separate container. Use 100 mg per litre of container water.

Tetracycline can also be used like Chloramphenicol as an addition to the feed, with the limitation as already mentioned that so often with Vibrio infections the fish will not eat. When attempting to use Tetracycline in the feed take 750 mg tetracycline HCL and mix same with 100 gram of feed. Use this mixture for at least one week, feeding twice daily in the morning and early afternoon. The feed that the medication is added to, should be highly nutritious and appealing to the fish , and beef heart ( as prepared by the method given in Untergasser’s excellent book , see references below), will appeal to such fish as may not be already to far infected.

Oxytetracycline . Use at the same dosage as Tetracycline above.

All of the above are antibiotics, and can only be obtained with a Veterinary prescription, in Europe and the UK

Please also note , that any of these antibiotics, are prone to disturb the Nitrifying bacteria in the filter bed. A very close watch during treatment, must be kept using high quality test kits, on the values of Ammonia and Nitrite. Should either or both of these important parameters, start to show meaningful measurements, then water changes and other corrective action must be taken without any delay, otherwise a potentially lethal extra problem will be added to the one under consideration. One can change the water, but far better is to only undertake these forms of treatment in a separate tank, when the problem, should it arise, can be remedied quickly and easily, by changing the water, sufficiently and frequently enough to keep the matter under control until the treatment period is over.

Revive . A company Fish-Vet has managed to produce a product termed ‘Revive ‘. This product can be used in fresh and salt water tanks , and also in Reef tanks, as it has no adverse effects on any Invertebrates or Corals. It has proven most efficacious against Vibrio infections as well as other gram negative bacteria, though NOT against gram positive. It has the unusual characteristic, that in salt water, one must use only half the dosage, which is the reverse of what most other treatments call for. Most remedies that can be used in fresh and salt water, use more in salt water. In the case of Revive , the higher pH found in salt water, acts as a potentiator which accelerates the effect of the drug, and it is important to pay attention to the instructions, as otherwise much harm can be caused to the fish.

We have had great success with this product, and a growing number of stores and Hobbyists now testify to its usefulness, in treating this and other bacterial scourges. It not only can be used in fresh and salt water, but has no effect on the water chemistry, nor most importantly on the nitrifying bacteria.

I am often asked ( about 6 times a week at least), if Revive can be used at the same time as the No-Ick product which treats Marine White Spot (Cryptocaryon irritans) . The logic of the question is that so often the White Spot parasite causes secondary bacterial infections, which in some cases at least will be Vibrio infections and in many others will be gram negative bacteria against which Revive is also effective. To try and pre-empt for some of you, who may wish to phone and ask this question, I know of no actual reason why one should not, yet I always advise against it. The reason is that any addition to the natural water, produces a strain of some kind on the fish, and no-one can be sure of the multiplying effect that these two, or any two medications can have in attempting a cure. The best advice I can give, is that if the need for both is indicated by the signs, then to finish the treatment and eradicate the White Spot first, then filter with a good quality charcoal for 24 hours to remove any residual No-Ick , and then add the Revive .

Like so many infections of fish, it is probable that Vibrios like many other pathogens, are really part of the background flora, in which the fish exist. Yet for reasons that are poorly understood, in some cases they have been detected, and yet never cause a problem, whilst in others, they just suddenly become pathogenic and cause wholesale havoc. There is a lot of research still needed to determine the actual reasons why one or the other should prevail. It may be that there are different subdivisions of the organism, which have not yet been characterized.

It may equally be, that some environmental parameter changes adversely, or that one fish, which becomes stressed or injured, causes the latent pathogen to assume a virulent form, which then can quickly spread to other fish, trapped as they are in a small body of water, i.e our Aquarium.

One other observation:- Each week I got calls or E Mail from Hobbyists, who have a problem, and are in some cases at least, in a panic to get a suitable treatment ‘yesterday’. I find it amazing that in this day and age, when the average household has a medicine chest full of common remedies, that Hobbyists most especially those, that have so often invested in their Hobby not inconsiderable sums of money, wait until disaster strikes before buying at least some of the most likely to be needed treatments. The cost of remedies versus the typical investment in a good aquarium is marginal, and some diseases such as ‘white spot’ in both fresh and marine tanks, usually occur, at some time. As speed of suitable treatment is vital , I would strongly counsel our readers to have at home the most called for drugs, as it repays in spades as they say, by being able to start treatment at the first sign of trouble, and the potential losses that this avoids, will repay many times over the cost of the small investment.

John Shawn Prescott john@aquarium-gardening.com

Bacterial Fish Pathogens Author B and D.A. Austin

Fish Medicine Author M.Stopskopf

Handbook Fish Diseases Author D. Untergasser

By John Shawn Prescott

This article was written after attending a fish disease conference in Edinburgh Scotland, where the EAFP (European Association of Fish Pathologists, had a conference, in the grounds of Heriot-Watt University. This event held every second year, brings together many hundreds of Fish Pathologists, who all have more or less the same interest. That is to say, they all work in some way or another, on fish disease.

Many of them, though not all, work in the area, of fundamental or applied research, but also many Veterinarians as well as others, who farm fish for a living attend the myriad of lectures on every conceivable topic, connected with the health of fish. As well as 3 parallel sets of lectures which run for 4 days, there are a few hundred excellent poster displays, often produced by students who are studying for their Ph.D. and use the occasion to demonstrate to a wider audience their particular area of research.

Several lectures raised matters, which I though would be of general interest to our readers, and in addition there was a session devoted to ornamental fish, their diseases and problems. I believe this is the first scientific conference of this nature, that ornamentals were given such a thorough airing, and it a tribute to the growing importance of the aquarium industry, throughout the world, as well as perhaps to the many common problems with aquaculture that such time and effort were devoted to it.

Among the speakers, was a Dr. Markus Biffar, a veterinarian who works for the very famous company of Aquarium Glaser, in Germany, one of the largest and best run companies in Europe, that exclusively import exotic fish. Dr. Biffar, a veterinarian who works for the very famous company of Aquarium Glaser, in Germany, one of the largest and best run companies in Europe, that exclusively import exotic fish. Dr. Biffar’s job is totally related to keeping the fish in the best possible health, and it is indication of how far our industry has progressed that today leading wholesalers, as well as retail shops who are serious about their business, find it worthwhile to employ such well trained specialists to ensure they keep one step ahead of the competition, as well as minimize the losses which are unfortunately an ongoing overhead in this business.

Dr.Biffar told the well attended lecture that although the aquarium trade is growing every year, that due to the many problems of disease, the industry needs more and more help, from qualified people, if the numerous problems are to be overcome. He also made a plea, that those companies that produce the countless filters, and other hardware devices should begin to produce proper scientific studies to back up their innumerable claims. This would also apply to the many treatments advocated by some 30 or more produces of medications for the Hobby worldwide.

As this writer has often commentated, he also emphasized that lack of optimum water quality which brought about STRESS, assisted infectious organisms to get a hold and run amok, when the resistance of the fish is lowered. He pointed out, that for many of the rarer species; even today we do not exactly know their specific requirements in nature, making it even harder to replicate ideal conditions. Thus companies like the one he currently works for are making intense efforts to develop state of the art diagnostic technology, for the enormous numbers of problems which are often different from fish to fish, and in fresh water alone amount to some 2000 species.

Another interesting lecture was given by Dr. A. Adams of Stirling University , which he produced by himalong with others, including workers from Kasetart University in Thailand. (This later University is one which the writer visited in May, as part of a major consultancy trip he was doing for a large American client), and the University is responsible for almost all the work on fish disease in Thailand, including most of the work, relating to the shrimp industry, in which Thailand is by far the world’s largest producer).

In this lecture Dr. Adams, related their findings in work done on Siamese fighting fish , Betta splendens. They found that Tuberculosis which is found in some 150 + varieties of fish, is often encountered in the Bettas, and although there are several forms of this bacterium, the one they encountered closely resembled Mycobacterium marinum.

They especially were concerned about this bacteria as it can be transferred to man. They reported that skin lesions caused by this infection had frequently been found in workers who came in contact with these fish that were infected. For those of you, who are not aware, a number of cases have also occurred in the western world, and it behoves anyone who handles these or other fish, to be most careful if there is any suspicion that this infection may be prevalent. The bacteria will thrive at temperatures of 37 degrees C , and this means in states such as Florida and other hot areas, extra precautions should be taken.

To date there is no way known to rid a person of the very ugly discolourations that such infection can bring about on the skin, even though the disease itself it can be arrested by modern treatment. The people in Thailand are now working with the latest in PCR technology, as well as other screening techniques to try and ensure that infected fish are detected before they are exported. However be aware that at the present time, there is no legal or other requirement that such fish be prevented from been sent abroad, and even if such were implemented, the cost of policing such a law having regard to the hundreds of producers, would be almost impossible to control.

Those of you that may have read my other articles will recall that I wrote on this precise topic, and I did not at that time know that such a specific lecture would be given in Scotland.

There were many interesting lectures, but one point that came out in several of them, which were dealing with detection of pathogens, was that the detection of a known pathogen was not necessarily an indication that the disease it caused would break out. Many forms of screening and detection using very advanced technology, such as PCR, DNA probes, ELISA and more, is the holy grail of people working with very large numbers of fish, such as are typically found on today’s modern fish farms. It is the business of the professional to try and find out at the earliest possible moment if a disease is present and likely to break out. This way so the theory goes, one can take suitable prophylactic action.

However perhaps to the chagrin, of the investigators, despite excellent advances in detection methods, they found often, and especially in wild fish as well, that pathogens that are known to cause specific diseases, were detected beyond any question of doubt, yet no disease developed. There is little question in my mind, that in many cases this is due to the fact that STRESS was not a factor, and that the pathogen, is just one part of the background normal flora, that is present very often in nature, and causes problems only when conditions become abnormal.

Again at the risk of being repetitious I would bring this all important point to the attention of all of you who keep aquaria. If you can maintain the water conditions, as well as the environmental parameters in accordance with good management practice, then even though the odd bacteria or perhaps a parasite may be present, the natural immune responses of the fish, will fight it off, much as we do when exposed to a cold etc. The addition of medication is too often used as a cure-all when more attention to water changes, good filtration etc, could have helped much more.

At the conference there were many lectures on vaccination technology and developments, and it does seem possible that in another few years, that some of the oral techniques now being pioneered by companies such as Aquaculture Vaccines Ltd, and others, will be able to be applied to our aquarium species, easily by the many producing farms, and at an acceptable cost. This is very important as perhaps you are not aware, that the DOA’s (fish dead on arrival) after importing or a few days after same, are averaging industry wide, some 20-25% of the fish. When one multiplies this figure over the industry, the figures of losses are staggering, and you dear Hobbyist, pay for all of this. The only people who gain are the airlines, who ship dead or dying fish at the same price.

Although enormous progress has been made in detection methodology, and some progress has been made in vaccines, it was disappointing that little progress has been made in really effective new drugs. This is partly at least because any new drug, must pass an enormous amount of bureaucratic scrutiny, in both North America and the European community. Although one is sympathetic to the need to ensure that we do not end up eating fish that could harm humans, due to their treatment, it sometimes seems to be carried to extremes. Malachite green, which is a known carcinogen, but a very effective anti-parasitic agent, is totally prohibited. Yet in young fish, most prone to such diseases as ‘white spot’, it can cure them in a couple of days, and there is no residual carried forward when they are ready for the table. Yet it is prohibited totally as I said. In fact in North America for the fish farmer, there are currently only about 10 ‘approved’ products that may be used on fish without restriction, and these include things like Garlic, and Hydrogen Peroxide .

Whilst in the Hobby at this time, we enjoy a wide selection of drugs which are freely available, (in the USA) I am informed on good authority that these days are drawing to a close, and that within a year or two more, they will find ourselves subjected to the same kinds of regulations that currently prevail all over Europe, where no non approved drug, may be sold except with a Veterinarian’s prescription.

Whilst I feel we have gone too far, in allowing all and everything to be sold freely over the counter, which in the case of antibiotics, is certainly causing resistant strains of bugs to evolve, it does appear to me at least, that with good will, intelligence, and some oversight, we should be able to improve things, without making life impossible, for those of us, that have dearly prized sick fish, and yet accept that some regulation is in everyone’s interest. What I would not like to see is another small army of Government regulators, making everyone’s life a misery.

The delegates who numbered over 500 from some 40 odd countries, including many representatives from Japan, the USA, Korea, Thailand, and much more, had a most fruitful week. The writer and his associate finished up the week on the Friday, with a tour (there was a choice of four), which was a visit to the oldest whiskey distillery in Scotland. This distillery appeared to be making much more money from its tourists conducted tours and sale of countless forms of souvenirs, than it could possible make from the sale of its malt whiskey, which they produced as they informed us some 400,000 litres annually. After an excellent lunch of Scottish specialties which included smoked salmon, for which Scotland is famous, venison which is now farmed extensively, and a dessert of raspberries, which that region produces copiously, we left to visit a trout farm in the nearby area.

The trout farm produces some 300 tons annually and sells some of the produce as finished table ready fish, others are grown on to a stage and sold to farms in the south of England, where the growing season is much longer. In that part of the world (Scotland), they only really get some 5-6 months actual growth. The farm is fed by a natural strong stream, and they informed the very interested party (all fish pathologists), that they vaccinated against Red mouth disease of trout, but for the most part hardly ever saw any other form of disease.

All in all a very interesting week, with a great deal of information to be digested. I do hope that some of you, will find this discourse on what we heard and saw, in some way relevant to your fish keeping, as in fact all fish share many common factors, and disease, its prevention and cure, is certainly one of them.

John Shawn Prescott john@aquarium-gardening.com