I have a flasher wrasse and they are lovely little fish but like ben's mine also jumped through the little holes in eggcrate!! So a solid top is advisable. I would also be careful adding new fish with a hawkfish in there!! Mine is incredibly territorial along with the sixline wrasse which are now both residing in my nano. It is funny because they show absolutely no aggression when they are introduced after other fish. My hawkfish is now being nipped by the clowns for sitting too close to their hammer!!
Regards