Crabs

There are over 850 crab species including freshwater and terrestrial types. Crabs are fairly familiar critters in saltwater aquaria. Overall, they are fairly resilient and adaptable creatures. They are certainly among the hardiest of the invertebrates. With their stout body, strong legs/pinchers and an extra rugged exoskeleton, these decapod crustaceans are built for battle; where their decapod cousins the shrimp are inclined to flee and hide, these scrappers often firmly stand their ground. Feisty and sometimes quite colorful, they have an eye-catching charm that earns the attention of most aquarists. However, because individuals of certain species can really be “jerks” to their tankmates, any crab should be (1) researched thoroughly prior to purchase and (2) carefully monitored, especially in the first few days after introduction, to be sure that it doesn’t go rogue. Most mid-sized to larger crabs are thus best kept out of reef tanks but are great in so-called fish-only systems with semi-aggressive fish such as large tangs and angelfish. Large wrasses, pufferfish and triggerfish, however, cannot always be trusted. Crabs (especially males, which in some cases may be identified by their larger claws) can be quite antagonistic towards each other. One is playing it most safe when adding mellower species such as the emerald crab, which is valued for its appetite for undesirable filamentous algae. Even safer (and really cool) are the smaller reef species such as the porcelain crab and pom-pom crab. In this section, you will learn which species are reef safe, which fish to keep with them and how to provide the best home and diet for them.