If it looks like ich, is it always ich?

[TBone303]

I have had a chromis in qt for the last 2 weeks and it has developed a white spot on its back fin which has been there for the last 2 weeks. At first I thought it was ich, but it has not fallen off the fish to complete its life cycle. Is it possiable that it could be something else. The chromis has no other white spots on him and it seems to be really healthy.

[fingersdlp]

If it is the same white spot then after 2 weeks I don't think it can be ick. I have a sailfin tang that has had a single white spot on a fin for several months. I think 3 -7 days is the typical time for the spots to stay on the fish so like you I don't think it is ick.