OMG! Today I found a hole on my Betta's dorsal fin. It's very small but I don't know what it is. It wasn't there yesterday.
I put him in a 5.5 gallon tank last Sunday (he came from a 1 gallon tank), it has a filter, some real plants and some fake plants (all are fabric not plastic), he has two toy columns that he likes to hangout in and I checked those and there isn't any sharp edges, and the water goes between 80-82F depending on the time of day. And, none of my aquarium stones are sharp either.
He didn't have a filter in the 1 gallon tank, so could he be stressed out about it? Would he be able to reach and nip his dorsal fin?
I couldn't take clear pictures but I'll try to get some pics and post them later. In the meantime what should I do about it? I've turned off the filter until tomorrow when I can make a water change, but what else should I do?