My Small Community Tank

Question
Hello, I have a small community tank the residents consist of: 2 Clawed Frogs, sucker fish, about 8 ghost shrimp & a beautiful beta Named Kudjo! We have natural rocks, a plastic plant and small cave. these fish have always live in perfect harmony & my beta in particular was extremely feisty and happy. We recently introduced a rainbow shark into the tank  we really dont see much of him sense he spends most of his time in the cave. But I did notice that after a week our beta would spend most of his time hiding and wasn't enthusiastic during feeding time! So today I was shocked to notice that his beautiful fins are all tattered & there seems to be what looks like feelers sticking out of parts of his skin... now what i cant determine is weather this is due to a parasite or its just bit marks from the shark??? For the time being we have put the beta in a separate tank, can you please help?

Answer
Rainbow sharks can be a little on the aggressive side especially since Betta's are territorial,and because they rest on the bottom a lot, they might have fought. The best thing you can do is keep the Betta seperate from the tank permanently, otherwise this will keep happening.  You may be able to try some fish medication to help the open spots, MELAFIX by API is really good just becareful and give less than the recommended dose because it's very easy for fish to overdose on it.