My friend had a young angelfish who was being attacked by her other fish. Overnight they ate almost all of his left side fin and half of the right. She had him in a hospital tank for a few days and now he has moved to mine where the fish are much nicer and he can heal. Just wondering how long it will take them to regrow and anything I can do to help the process? It's very sad because he can't stay upright, he keeps swimming sideways but has been getting better the past few days.