Please help!!!!

[Goldenpuffer11]

I have a 10 in. Completely yellow golden puffer and he is not doing well. White spots started to develop near his back fin and the fin looks torn, he has stopped eating and not swimming much. Any information on this issue would be great.

 

[Nina51]

can you post a pic? did you put him in your display tank or quarantine tank? any other fish in the tank with him? how long have you had him?