Tag Archives: aquarium virus

What Are Iridoviruses?

Iridoviruses are a family of viruses (130–300 nanometers in size) that contain DNA as their genetic material and have an icosahedral (20-sided) capsid. Iridoviruses have been found in a wide variety of fish, including both freshwater and saltwater species.
Some iridoviruses have been associated with serious diseases (e.g., viral erythrocytic necrosis of salmonids) while others have only been found in apparently healthy animals (e.g., goldfish iridovirus).
One iridovirus causes a disease called lymphocystis which causes unsightly skin lesions on infected fish, but otherwise is of little consequence.

Iridovirus in Gouramis

An iridovirus was found in spleen and intestinal tissue of gouramis from the genus Trichogaster that were dying with signs of systemic disease. Mortality rates of affected fish have varied from low (0.5–10%) to moderate (50%) with death usually occurring 24–48 hours after the onset of signs. Clinical signs associated with the presence of the iridovirus have included darkening of body coloration and lethargy. Sick gouramis often stop eating and the abdomen may be distended. Internally, an enlarged spleen has been the most notable abnormality. The intestine may be reddened, and a clear amber fluid may be present in the body cavity. Laboratory examination for bacterial, fungal, or parasitic agents has frequently been negative. Through electron microscopy (EM), abundant iridoviral particles have been found in the spleens and intestines of dying fish.

An iridovirus has been isolated in cell culture and cytopathic effect (death of infected cells) has been observed. Although the iridovirus has been implicated as a possible cause of disease in gouramis, efforts to reproduce the disease under laboratory conditions have not yet been successful.

The picture below shows a Dwarf Gourami displaying symptoms that are sometimes found with DGIV (Dwarf Gourami Iridovirus). Often darkening of the body is also a classic symptom too.

Very little can be done for a fish with Iridovirus, often euthanasia is the best course of action.
Treatments to consider would be a Medicated Fish Bath along with a Medicated Wonder Shell in tank.
Resources:
*Fish Baths, Dips, Swabs
*AAP Wonder Shells; Regular & Medicated. The ONLY Authorized online seller

Level One UV Sterilization can also help with prevention both by killing any viruses outright that pass through the ‘Category A’ UV Sterilizer and by improving Redox Balance.
Proper flow rate, installation, even the correct UV (as many now sold are junk), and proper maintenance (which includes changing the UV Bulb) are essential this tool being effective for prevention of Iridovirus in Gouramis.