not to be a jerk here, But this is how poor fish decisions are made. The hawkfish is not a bad fish to purchase per say, but just buying a fish without doing any research on it is not a smart move. thats how people end up with bubble tip nems, mandarin fish and moorish idols in brand new tanks that both kick the bucket immediately all because someone was too impulsive to do 5 minutes of research. Not only is it a living animal, but its an animal that was not captively bred it came straight from the ocean and a dead animal puts more demand on more fish to be re caught and then sold again only to die with another person that didnt do their research.
Now that I have stated my emotionally involved opinions, the hawkfish will usually eat ornamental shrimps. they likely will not stand a chance. Also hawkfish can and will eat smaller fish. its mouth will get larger than you would think. It will also attack other elongated fish like firefish. I would cover the top of your tank if you do not have it covered already. they are known to be jumpers. and the last thing anybody wants to see is their brand new fish fresh off a carpet surfing session. good luck with the fish and I hope you enjoy it and please do some additional research the next purchase you make.