I recently left and stayed at my friends for a weekend so my grandma was left to feed my fish. They didnt eat through a whole night and morning but were fed the following night. When i came home i realized they were in bad shape, with my bigger bala shark, who is about 5 inches. He had a big part of his right side with scales missing and it was bloody looking. The blood has cleared up but now theres a piece of skin or something hanging off. The scales appear to be healing, but im wondering. Could this be the other ones nipping at it? and what should i do?