Waspfish (Tetrarogidae) are typically found lying on the bottom, imitating algae or bits of debris. Some even have algae growing on them which means that algae eating fish can cause injury.
They feed mainly on small bottom dwelling crustaceans. They might try to catch fish but are not particularly adept at catching them. It is by no means certain they can get used to frozen foods, but one might be successful over time.
Waspfish are not particularly fast and therefore cannot compete for food with faster swimming fish and consequently will not do well. They do not normally pose a threat towards other animals in an aquarium, it is only small crustaceans and very small fish they will prey on.
They have very poisonous spines on their back and this, combined with their habit of camouflaging makes them dangerous when having bare hands in the tank. Take special care not to damage their spines when they need catching.
Anemones and corals that burn strongly can injure Waspfish.