I had put up a post before about my naso tang and his possible parasites. He eat's really well but is still very skinny. i'm more worried about him now because his swimming has become less active. Instead of swimming around actively he sort of sits there and floats around. Occasionaly he will zip around if he is chasing my idol away or when i put food in the tank but most of the time he is very come and not active. what should i do?