Dwarf Gourami IRIDOVIRUS

Gourami (Photo credit: Wikipedia)

General Hardiness

Over forty years ago I first kept and bred Dwarf Gouramis. At that time they could reasonably be described as a hardy fish. Unfortunately the ones we get nowadays have lost much of this hardiness. This loss of hardiness seems to have been caused by several different things.

They have been selectively bred, producing a number of different colour variations. It is likely that many of these are inbred, and suffer from the lack of vigour frequently caused by inbreeding.

Most of the Dwarf Gouramis bred in places like Singapore will have been kept in controlled conditions and individuals which would have died out quickly in the wild will have survived and often been used for breeding. Related to this is that in captivity fast growth would have been selected for, and particularly fast growth under the near forcing diets fed to commercially bred fish. The fast-growing fish are often not as hardy as wild ones.

Disease

Related to the lack of hardiness in many commercially bred Dwarf gouramis is the fact that many of them are diseased. They are susceptible to normal aquarium fish diseases, but one is of particular concern. This is the Dwarf Gourami Iridovirus.

This disease kills the Dwarf Gouramis slowly, sometimes taking as long as a year to kill them. The symptoms include wasting of the fish and there is little doubt that before this disease was identified, fish tuberculosis was blamed for some of the deaths from this virus. This virus may have become a problem because of the extensive inbreeding of this fish in Singapore.

Many virus diseases are specific to a single species, and it is frequently reported that only Dwarf Gouramis can get the Dwarf Gourami Iridovirus. However, there are also many conflicting reports.

One study by a team led by Professor Richard Whittington of the University of Sydney, Australia found a 99.95% genetic similarity between the Dwarf Gourami Iridovirus and a virus outbreak in 2003 that killed farmed Murray Cod, Maccullochella peelii peelii. A test showed that Murray Cod can be infected with the Dwarf Gourami Iridovirus, and had 90% mortality.

There is fear that the Mosquitofish (Gambusia species) can act as a carrier for this virus and aid its spread through wild fish populations. This virus has also been reported as affecting swordtails.

One of the problems with these reports is that there are many types of fish Iridoviruses. Some of them will kill or make the fish ill while others seem to have no bad effects on the fish. To really find out what is happening would take a major research effort.

Several internet articles say that 22% of Dwarf Gouramis coming out of Singapore have this virus. This figure is actually based on a study of Dwarf Gouramis in Australian retail aquarium shops. The study found that 22% of these fish were infected with this virus. All the tested fish had been imported from Singapore. The fairly reasonable jump was made to state that 22% of the Dwarf Gouramis coming out of Singapore were infected.

Of course, all the tested fish would have been through quarantine and any fish showing signs of the disease would have been destroyed. If any batch of fish had a lot of diseased specimens the whole batch would have been destroyed. If an importer loses a whole batch of fish he has lost a lot of money and would look for another supplier.

At least one normally reputable internet site says that most of the fish coming out of Singapore are infected is a very worrying figure, but it certainly is not "most".

Government Action Needed Now!

The trade-in ornamental fish is a major part of Singapore's trade. If there is a problem this serious with Singapore's fish, it needs to be fixed.

Some years ago, a large ornamental fish farm in Australia had a serious problem with fish disease. With government help, they systematically eradicated the disease. This fish farm now has an extremely good reputation for the quality of their fish. Unfortunately, they do not breed Dwarf Gouramis.

The government of Singapore needs to recognise that there is a serious problem and to solve it before Singapore's export trade in fish is ruined.

By Steve Challis - Article Source: EzineArticles

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AQUARIUM FISH death: precautions of young aquarist.

Small Aquarium with Paracheirodon innesi (neon tetra), Trigionostigma heteromorpha and Hemigrammus erythrozonus
(Photo credit: Wikipedia)

Another thing to watch out for in a newly installed tank is the quantity of food: very little of this should be given during the first three weeks. Mind you! I am not suggesting that you should not give them food at all, because without food, no bacterial flora forms. The food supply to the bacteria should be increased only very gradually.

Fish keepers with old functional aquariums should avoid general cleaning that is washing of sand/gravel, scrubbing of the tank wall and complete water changes so as not to disturb the bacterial flora.

When you have to service, it should just be the removal of the mulm and dead leaves sufficient to ensure adequate flow through the filter and no more. The bad habit of replacing the entire filter material or the soiled part with fresh materials is detrimental to fish life. Most bacteria live in the sludge at the bottom of the tank, so don't throw them away.

Many pet shops that operate a house-to-house maintenance routine on aquariums are used to the habit of a complete overhaul which invariably lead to fish death. I have met many people who have said, "I used to service my tank myself. On close scrutiny, I discovered that he indulges in the unforgivable habit of washing the aquarium with detergents!

In real life situation, no one can attest to having experienced a complete overhaul of a river bed. The only thing that happens during heavy rains or flood is the partial/complete change of the water body. The bed, sand and gravel components get cleaned but not overhauled.

This is nature's method of 'servicing' the fish's natural environment. So why don't we all adopt nature's method? Professional aquatic pet dealer’s service aquariums in the same way, and to the committed aquarist, I will advise you to do this yourself!

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FISH PARASITES

Myxobolus cerebralis, a myxosporean parasite, causes whirling disease in farmed salmon and trout and also in wild fish populations. (Photo credit: Wikipedia)

There are certain types of parasites out there that affect fish. They can become a very serious problem though. They can result in the fish not growing like they should. They parasites can become so bad that they result in the fish dying. This is a common issue in many areas. As a result, they can die off in a complete area without any way to survive. Other creatures that depend on the fish for food will not be able to survive in that location either.

These types of parasites tend to only be a problem in areas where freshwater fish live. There are ways to remove the parasites from the environment though but before you start to use chemicals to destroy them. You may end up doing more damage to the fish than helping them out. The biggest type of fish parasite is the protozoa classification. The good news is that they are the easiest form of a fish parasite to destroy.

There are several different species of fish parasites that fit into the category of protozoa. They can generally be eliminated by adding copper sulfate to the water. Some people add it on a regular basis in a pond of fish just as a precaution so that they don’t lose their valuable fish to parasites. 

If you find your fish in the pond are having more trouble then usual surviving you may need to check to see if parasites are the problem. Some indicators that you may have fish parasites to contend with include them losing weight, not eating like they should, and a high number of them are turning up dead. 

You can’t see them without a microscope though. You can get a specialist to come in and test for them. This will also help them to determine what type of fish parasite you are dealing with. Finding the best course of action to resolve the issue is going to be in your best interest. 

When parasites invade fish in a wild environment though it is more difficult to take care of. They can be more vicious too and they will destroy the fish population from the inside out. The local Division of Wildlife will have to evaluate the situation and decide what course of action to take. They want to do what is best for all of the creatures that live in that area. 

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