Help to ID an unhealthy growth

[RelativeFishBeginner06470]

Hello.

We've had 3 cories for a while in a very healthy, planted, and well-cycled tank.

One started to develop a growth on its gill, and it does not look fungal (i.e. no fuzzy texture). This was about 2 weeks ago. Since then, we have quarantined it and have treated the water with the following at the directed intervals and doses:

Jungle Fungus Clear
API Melafix
Fritz Coppersafe

This fish is usually in a school of 3 cories, and the other 2 appear healthy with normal behavior. The quarantined fish is also behaving totally normally in a 1 gallon quarantine tank at 76°. It has been eating and digesting without issue, too.

Does anyone know if this growth is potentially a tumor and, if so, should we just return the fish to it's usual habitat?

Thanks in advance for your time and help.

- Greg & Jess

 

[Colin_T]

Gill tumour. There's no cure so put it back with the others. When the fish has trouble eating, swimming or breathing, euthanise it.

 

[RelativeFishBeginner06470]

Colin, thanks for the advice.

It is much appreciated.

- Greg & Jess