Join Date: Mar 2009
Location: Vancouver, BC Canada
I wouldn't worry about that. I wouldn't even have seen whatever this is if you had not mentioned the adipose fin (that is the name of the small fin just before the caudal or tail fin).
I may have seen similar on my fish, but I'd have to see the fish itself before being certain. If it has been a week and no other spots are visible, it is not likely related to ich. Are any of the fish flashing? Flashing means swimming fast against a leaf, wood, rock or the substrate in an attempt to rub the gill area. Ich always first attacks the gills, and flashing might indicate ich even if no spots can be seen. I still don't think this spot is ich.
Byron Hosking, BMus, MA
Vancouver, BC, Canada
The aquarist is one who must learn the ways of the biologist, the chemist, and the veterinarian. [unknown source]
Something we all need to remember: The fish you've acquired was quite happy not being owned by you, minding its own business. If you’re going to take it under your wing then you’re responsible for it. Every aspect of its life is under your control, from water quality and temperature to swimming space. [Nathan Hill in PFK]