Originally Posted by
jmf3460
Heidi, since you have already started the malachite/formalin treatment I would continue for 3 days then add carbon to remove completely. Then do a large water change and monitor. I would not have suggested the treatment in which you have chosen, malachite and formalin are mainly going to cure diseases/fungus/parasites on the external body of the fish, not internal. I think the bump you see is more of an internal issue. While I do not think it is a disease at all, it may be beneficial to start a treatment of metro or levamisole once you have concluded that it is not simply a genetic defect.
Does the fish defecate normally? Normal color and consistency?