Not a clown goby, but a randali goby. No issues in 2 years. My flame was in the tank first (moved ther upon setup after 15 years in my previous tank, the goby added about 3 months later. The randall's goby stays on the bottom and hides under rocks. My hawk sits on anything, but usuall rock or coral, seldom on the substrate.
My hawk is very assertive at feeding times (or asking for feeding time when someone walks by the tank), but is not aggressive. I think he got a little too pushy when I first introduced my foxface and got stung. Learned his lesson quick if that was the case.
Kim