Arrow Crabs are excellent scavengers and safe for most aquariums.  They are a very unique crab that is naturally suited for controlling bristle worms in reef aquariums.  If no bristle worms are present, they will eat most fish foods, such as pellets or frozen meaty foods- like krill or mysis shrimp.  They do not bother fish or other crustaceans, however, if they are not fed properly they may nibble on snails.