Dwarf Gourami Iridovirus: symptoms, treatment, prevention

Dwarf Gourami Iridovirus (ISKNV-related) is an incurable iridovirus endemic in farmed dwarf gouramis; affected fish must be culled and stock from unknown sources avoided.

Overview

Dwarf Gourami Iridovirus is caused by an iridovirus related to Infectious spleen and kidney necrosis virus (ISKNV). It is endemic in farmed dwarf gouramis (Trichogaster lalius), with about a fifth of trade stock estimated to be infected. There is no cure, and the disease is usually fatal once symptoms appear.

Symptoms

Loss of color
Skin sores and ulcers
Swollen abdomen
Lethargy
Anorexia
Chronic ongoing mortality in the species

Causes

The virus is endemic in mass-produced dwarf gouramis; introduction occurs with new fish from unscreened farms. Direct contact and contaminated water spread it within a tank.

Diagnosis

A pattern of multiple dwarf gouramis sickening with skin ulcers and chronic mortality strongly suggests DGIV. Definitive diagnosis requires PCR by a fish veterinarian or accredited lab; clinically rule out bacterial septicemia and ulcerative columnaris.

Treatment

There is no antiviral cure. The realistic step is humane euthanasia of affected fish and biosecurity to prevent further spread.

Quarantine

Symptomatic fish must be isolated; never move them to another tank or share equipment. Survivors should be considered carriers and not used for breeding.

Medication

No antiviral cure exists.
Affected fish should be humanely euthanised to limit spread.
Do not purchase dwarf gouramis from unknown sources; use only ISKNV-free stock from reputable breeders.

Recovery

There is no meaningful recovery from clinical DGIV. After an outbreak, disinfect the tank, dispose of substrate, and observe a long fallow period before introducing new fish.

Prevention

Avoid mass-produced dwarf gouramis from unknown sources
Buy from quarantined breeder stock
Do not mix gouramis from multiple sources
Long quarantine on suspect fish