I have a male veil-tail betta in a 10 gallon with an African Dwarf Frog. I've only had this betta for about three weeks. I noticed later that his dorsal fin had a slight curl to it, but not in the way that would indicate fin rot. Since he didn't have any issues swimming or develop any further symptoms, I kept him... I came home today and now half of his tail is missing. He still isn't exhibiting any other symptoms of fin rot, but he is definitely having more issues swimming. Could the frog have bitten off his tail? Neither have ever displayed any aggression toward each other, but I've never kept African Dwarf Frogs before. Is there any way I can treat/restore it?