strange growth on Bagaii Cardinal

[CadetMKultra]

My Bangaii has a growth on one side, just forward of the gill slit. It looks like a pimple. Not a pimple scaled down to the size of a fish though. It looks like a big honking human zit. It's been hard to get a clear picture of it, but I will try again. Any ideas what this might be?

 

[CadetMKultra]

Also, the fish doesn't seem to be scratching or swiming strangely at all.