Hi. I have an emerald cory cat that is missing his entire tail fin! I'm really not sure how it happened, just that I saw him one evening with a bloody pectoral fin (or at least it looked like blood) and then about four or so days ago I saw him after, it had been probably a week, and he had a stump for a tail. It looks like now it's starting to grow back but now I'm wondering if he might be better off in my cycled five gallon alone? The tank he is in now has medium sized gravel, where the five gallon has sand. I don't want to lose him! He's one of the original fish added to the tank almost a year ago. Should I leave him? Move him? He seems to be doing alright and I wouldn't bother except I know cories (THIS STUPID PHONE!!!) like sand. There isn't anything sharp in the tank that I can see anywhere and I was wondering how... I recently had a bad bout with ich but that wouldn't remove tail fins, would it? I do have a large angelfish that recently developed a taste for live fish though (unintentionally fed him one of my guppy fry) and wondered if he was bullying the cory. Before he wasn't too aggressive but now it's much worse.