Arrow CrabHow to Care for Arrow Crab written by Dave Burr The Arrow Crab uses its very long legs to walk over the reef and to climb over almost any obstacle. Behavior: It rarely bother corals, however the occasional large specimen may pick at small passive fishes. Some Arrow Crabs will eat troublesome bristle worms. Overall, a great reef inhabitant that can live for several years in the home aquarium. Growth: Maintaining proper Ca, Alk, & Mg levels is important