The Dwarf Gourami Iridovirus is a fatal disease that commonly affects Dwarf Gourami, but is also known to prove to be fatal to any Anabantid fish (Betta, Gourami or Paradise Fish). In the past this disease was noted to be a type of bacterial infection which would case more damage and lead to death, however in more recent years this disease has made itself known even to the most safest and healthiest breeders. Due to the odd nature of this disease, even the most healthiest fish can appear to not have Dwarf Gourami Iridovirus until many months or years later.
Viruses can be transmitted between fish by either direct contact from rubbing against each other, to eating each other's fecal matter, to even leaving scales or skin on any decorations. Symptoms can range from lack of appetite, breathing more heavily through the mouth and/or gills, lose of control over their swim bladder, and most importantly a enlarged spleen which will appear like the fish is bloated.
As the disease progresses we can see the final symptoms will include the fish being unable to swim to the surface of the water to get air, their coloration may appear to be very dull or dark with some gray areas, and the fish will lay at an angle or flat on the bottom of the substrate. At this point there may be additional bacterial infections which can present themselves due to the lack of a strong immune system.
Dwarf Gourami Iridovirus is mostly spread across populations due to bad breeders who do not take care of the water parameters or overstock their breeding tanks. As the fish stay within contact with one another, all it requires is for an affect fish to have stayed in the same water or leave any trace for the next batch to get this disease. In a vast majority of cases, this viral disease is actually shared before being shipped to the store's tanks where it comes into contact with other fish that might not be infected at all. Even though many stores who sell fish do quarantine any new arrivals, it can be hard to determine which if any fish is infected due to it not showing any symptoms until the fish's immune system becomes weak.
Even when the new arrivals of Dwarf Gourami are healthy, once the viral infection starts to take over it can make this same healthy fish sick in a matter of weeks. Since Dwarf Gourami are highly wanted fish due to their colors and their personalities, this disease is most common across the various breeds of Dwarf Gourami that are sold around the world. A recent study showed that on average 22% of Dwarf Gourami that are shipped from Singapore carry this disease through tests done at various breeding locations on random samples of Dwarf Gourami.
Treatment and Medication
As with any viral infection or disease, there is no known cure which can fully cure the infection. Using a bacterial and fungus medication from various reports state that it slows down the rate at which this viral infection takes over the fish, there is no known documented proof of such. There is current research that is going on in regards to understand how this viral infection takes over the fish, yet no results have been published.
The best prevention is always to make sure that you are buying from trusted, well known breeders that take care of their livestock. Many will make sure that when new shipments are coming in from breeders that they look at all of the sick, dead, and even healthy fish for signs of disease. This through examination can provide to be highly beneficial as it can reveal any signs of any possible disease which the fish may now share. Since the rate at which this deadly disease effects its inhabitants, using quarantine methods may never show any symptoms until later in its life-cycle.