KOLE TANG HELP

[dawgs]

I bought a kole tang last Friday from a LFS. The fish had been in the store for a while and seemed really healthy not to mention this is a pretty hardy tang. Anyway, he seemed great in my 75gallon tank for the first 3 days. Yesterday he started not eating very well. Would only eat if the food went right by him, and then today he didnt eat at all. He also is not as active as he was the first days. My ph is at 8.4. Salinity is at 1.023, no nitrites, 8 nitrates, and a very small amount of amonia. I have a skimmer on the tank, along with a uv sterilizer. Is this a bacterial infection? If so, what should I do. The other fish in my tank seem healthy. i have a fox face, tomato clown, and a flasher wrasse. i do have about 20 snails, 6 hermits, and a starfish in there.

 

Please help