Rainbow with big white spot on belly


13 Aug 2015
Just noticed this morning one of my red laser rainbows is doing poorly. Seems to show signs of clamped fins and has a big white spot on it's belly. Can't really see any other spots so not sure whether it is white sport. Also a slightly raised scales. Can't really get a good photo of it unfortunately.
Probably something related to stress has there was something wrong with my tank last week, fish weren't active at all for a couple of days, probably CO2 related but cannot be sure has pH was the same.

Any idea what it is and what I can do about it?

Tim Harrison

Super Moderator
Staff member
5 Nov 2011
The sticking out scales are often a sign of Dropsy, which is not a disease in itself but rather a symptom. The scales stick out because of swelling due to a build up of fluid in the peritoneal cavity http://badmanstropicalfish.com/fish_palace/tropicalfish_disease_identification.html#Dropsy
Fish sometimes also get tumours, lesions, growths or cysts which could be a symptom of an underlying oncological condition.
If they are large it's unlikely to be the result of a parasitic infection like whitespot. For instance, a couple of my ancient neon and cardinal tetras have a single white cyst on their flank and don't seem any the worse for it, I just put it down to old age.