sick fish

[nckissmrt]

i have a 55 gal. tank and ive had it about 6 weeks. i have a royal gramma, lawnmower blennie, and watchman goby in it. thayve all benn doing fine until recently when my gramma developed what looks like a pimple at the base of his fin. it still acts the same and its appetite hasnt diminished but it doesnt use that fin any more . any idea what it might be?

 

[bigarn]

Originally posted by nckissmrt
i have a 55 gal. tank and ive had it about 6 weeks. i have a royal gramma, lawnmower blennie, and watchman goby in it. thayve all benn doing fine until recently when my gramma developed what looks like a pimple at the base of his fin. it still acts the same and its appetite hasnt diminished but it doesnt use that fin any more . any idea what it might be?
What are your water parameters? At 6 weeks there shouldn't even be fish in there.