Bala Shark problems

[cj049678]

I bought two bala sharks to put in a 80 gallon tank with tiger barbs and a red tail black shark. One of the balas was being chased by the barbs. I noticed that its top fin has what looks like a bite mark. I moved it temporarily into a smaller tank. I checked the ammonia, nitrite and nitrate levels and they are all good. It has started to roll onto his back a lot and then right itself and act fine. What could be wrong with it. The tank is a 20 gallon but I am only keeping it in there until it gets bigger to put back into the bigger tank. Please give me some advice.

 

[Aquanero]

How many Tiger barbs do you have? Tiger Barbs are notorious fin nippers if not kept in groups. If they are kept in groups of 6 or more they pay attention to each other and rarly bother other fish.

 

[cj049678]

I have 6 barbs. The store I bought them from told me I had to buy at least 6 or more. They still picked on the bala so I don't know if it was sick and I didn't know it. So to protect the bala I moved it into a 20 gallon with 5 tetras until it got a little bigger to move back into the big tank. The tetras didn't bother it so I am hoping it gets better.