Originally Posted by blizowman1
It could be from the rocks or it could be from aggression from another fish. some times poor water quality will cause fin rot too. I had one of my Cory's out of a group of 8 thats find rotted off and it stayed small and eventually didnt make it but I think it might have been a genetic defect but yours looks pretty healthy to me I wouldn't worry to much about it.... What kind of Cory is it
He seems to be behaving normally and I haven't noticed anyone picking on him...it's usually my serpae tetras who my platy picks on (he's kind of a jerk, but he's been a survivor when others haven't!)...I've never seen him harass the Cory. Based on pics I've seen of cories, I'm pretty sure he's a peppered Cory. I've had him for a few months.