Help Black lesion on Dwarf Gourami


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I bought a beautiful male dwarf gourami about 4 weeks ago. 2 weeks ago he developed a black lesion on one of his sides, which seems to be very slowly growing. It is about 2-3 mm, maybe 1 cm back from his gills. He is active and eating normally. He is alone in a 10g quarantine tank; parameters are good and I test regularly. I have medicated with general cure, maracyn and ich-x for last week, and added 1 tbsp of aquarium salt today. No change in the spot. Any idea what this is or how else to treat? He isn't acting sick, but the lesion is troubling and I fear it is the beginning of something serious.

Here is a blurry pic. Sorry he won't stay still.

One more pic



Well Known
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Parma, Ohio
3 years
I am no expert but have seen similar stories with similar things on different forums. I wanted them at one time due to their colors, but I read about this virus they could get and I think it is very likely your fish has it. Below is some information that I have found on it.

Dwarf Gourami Iridovirus (DGIV)

The quality of the dwarf gouramis in the trade has steadily declined for years, with batches of fish showing significantly higher levels of mortality than 10 years ago. Historically, retailers and aquarists have blamed bacterial infections, such as fish tuberculosis (Mycobacterium marinum). In recent years, though, attention has focused on a virus known as dwarf gourami iridovirus or DGIV.
Dwarf gourami iridovirus is apparently specific to the dwarf gourami (Colisa lalia), including the various fancy varieties of the species, such as neon gouramis and sunset gouramis. Infected fish develop a variety of symptoms, including loss of color, decrease in activity and appetite, the appearance of sores and lesions on the body, abdominal swelling and finally death. This fish disease is highly contagious, completely untreatable and invariably fatal.
Dwarf gourami iridovirus is apparently very common. One recent study of fish exported from Singapore found that 22 percent of all dwarf gouramis carried the virus. Aquarists should never purchase dwarf gouramis from fish aquariums containing fish exhibiting symptoms consistent with the dwarf gourami iridovirus, and all new fish should be quarantined for at least six weeks prior to being placed in the main fish aquarium.
For most aquarists, my best advice is to keep the hardier alternatives to dwarf gouramis. The thick-lipped gourami (Colisa labiosa) and the banded gourami (Colisa fasciatus) are both similar in size, temperament and coloration and make excellent alternatives.

I hope I am wrong, but if not, at least I could help.


Fishlore Legend
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Holland (The Netherlands)
More than 10 years
I doubt this is a case of Iridovirus and even think it is natural pygment.

To be honest : The possibility this fish is killed by an overuse / misuse of meds and treatment for "something" that isn't diagnosed is by far bigger than any disease. The tank's and fish's (immune)systems are destroyed. Simply stop throwing in everything available.

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