I recently got 2 fantail goldfish. One of them had been picked on at the pet store and it looked like his fins had been chewed on by the other fish. I got them home and they seemed to adjust fine. His fins seem to be regenerating a little and it didn't seem like there was anything else wrong but this morning I noticed the ends of his fins seem to be turning black as well as a little dark coloration around his lower stomach area. He doesn't seem to be acting abnormally. He swims around fine and though he is nervous he doesnt seem to try to hide behind anything or go to the surface unless he is eating. His appetite seem normal and also the other goldfish seems to be acting fine. He likes to hide a bit but other than that he is perfectly normal.