Maybe your hawk (couldn't find that species you mentioned) will get to only 3", but the write-ups on the ones I found said "don't be surprised at what they can or try to stuff in their mouths". Also said they prey on smaller fish and inverts.
So, if it were me, I'd trade him in.
Check out gobies (check out pistol shrimpand shrimp gobies too) and blennys. Also, if the hawk was gone, I'd still try to get the chromies going. Maybe 3 of'm. I'm not a damsel fan, but if they were added last, there might not be a problem.
If trading in, may consider either trading the single perc in for a pair or try to get one much smaller than the one you have now. Hoepfully they can pair up. It's fun to watch fish hang out together.
Lemme know what you decide.