Does anyone know what is wrong with my fish in this picture?

[kiki]

This fish has that thing on it's mouth for few months now. So far I tried Melafix twice. That thing on the month does not look like a cotton. It looks more like extra skin or maybe a tumour. It does not affect other fish. This fish still act like other healthy fish. Does anyone know what is wrong?

Has anyone here tried using nystatin/Nilstat in their aquarum?

thanks

 

[Allivymar]

Yep; I'm pretty sure thats a tumor. Nothing you can really do. As long as its not affecting the fish's ability to eat, I'd leave things. If it does tho, you will want to euthanize the fish, else it will starve to death. Has it gotten bigger or just stayed the same?

The pic on the left is very clear btw; really makes diagnosing easier - thanx!