Crabs for the most part are fun to watch. But most are omnivores or will eat everything that they can get their claws on. I had bought a arrow to help with bristleworms which he did until he learned how to catch gobies. Even some of the hermits that we buy for algea control will not only catch snails fo new homes but will catch fish when sleeping. I won't tell you what to do. Crabs are good and bad

jimbo