Brackish water stone fish won't eat Help!

I bought a brackish water stone fish a few months ago and he has been a pig. He literally ate his only other tank mate within 10seconds of being put in the tank. He is feed shrimp and tilapia with some live goldfish as treats. For the past 6 days he just refuses to eat anything at all. He won't even take life food. I'm very expierienced with brackish fish but I don't understand why he won't eat. He is in 73degree water with a 1.014 specific gravity with normal water parameters. Any help on getting him to eat or diet advice for the future is greatly appreciated.

 

Goldfish are not healthy at all for fish. Especially dropped in from pet store fedders should be gut loaded as well. It could be that it ate a bad fish or something. Whens last time it ate and what did it eat?

 

He only gets the gold fish as treats 1-2 times a month. The last thing he ate was a thawed out shrimp without the shell or tail and that was 6 days ago

 

Do you always keep the specific gravity at 1.014? You can drop the SG to 1.002-4 for a few days to kill off bacteria.

 

A lot of fish will refuse to eat anything but live fish once they know they're on the menu... another good reason not to feed them to fish that don't need them. Also goldfish contain thiaminase which blocks thiamine (vitamin B) uptake.

What species is it?