A few days ago we noticed his fins were shredded, from catching on things or biting. He also had a bit of white fuzz on them. We put in aquarium salt to treat what we thought was columnaris, and two days later the fuzz was gone. We changed his water again to get some of the salt out. Today, his tank is murky white (bacterial bloom?) and he seems to be shedding his slime coat. Any suggestions?