I found one of my galaxy rasbora look funny and after close inspection it look like lost chunk of flesh/scale/skin on the body. It is the only galaxy has the problem while it still swim and eating fine.
I am not surer what could cause it. Could some fish attacked him? The thing is if it is attacked by other fish, the fins remain intact and The largest fish I have in my tank is Simease algae eater. I believe there was a pair of peacock goby in mating mood and I read Peacock goby will aggressive toward smaller fishes if they are breeding.
Is it some kind body rot?