Though they are called crabs, they are actually more closely related to lobsters than true crabs. If you want to get hermit crab for your tank, there are a few hermit crabs you can consider. This does not matter because hermit crabs are clever enough to use a tough ready-made shell to protect the softer parts. Hermit crabs can be found in many habitats, on land, on shorelines and in deeper waters. The exotics are imported to the United States from the Pacific Rim. This is by far the most common type of Hermit Crab on the market today. They do well in any environment and are generally peaceful. This wide range of invertebrates can vary in size from small to very large. Hermit crabs are a type of decapod crustacean belonging to the superfamily Paguroidea. Because of their tiny size, these hermit crabs can really get into those small spaces in a reef tank that other hermits cannot. Native to the reef faces and coral rubble of the Caribbean, these active scavengers can consume large amounts of animal matter and algae. Another species of hermit crabs, the Coenobita rugosus, looks very similar to the Ecuadorian crabs except for a few key differences.The rugosus, or ruggie, comes in a variety of colors: black, blue, tan, gray, peach, and even white. In general, hermit crabs need saltwater for mating and molting purposes; but some hermits come from areas near freshwater. Hermit crabs spend most of their lives living in shells but, unlike snails, they do not grow a shell of their own. It is highly likely that if you live in the United States, you have one or both of these two species of crabs. The Scarlet Reef Crab … Found in nearly all marine environments, Crabs can range from less than an inch to over 12 inches in diameter. As hermit crabs grow, they have to discard their shells and look for larger ones. What Types of Hermit Crabs Should Be Placed in a Saltwater Aquariums. Saltwater hermit crabs love to climb on rocks so make sure to put some rock in your aquarium. Crabs are scavengers of any type of edible matter they find, providing an invaluable "cleaner" function, consuming both undesirable algae and detritus while mixing the sand. The minimum advised water volume for keeping saltwater hermit crabs is 10 gallons per hermit crab. Some remain very small, only 1-1.5 cm in size, while other species in this group reach a length of fewer than two inches. Small hermit crabs of the Genus Calcinus found in Hawaii are extremely efficient little critters. Knowing whether your hermit crab can go in freshwater depends on what type he is. Some Crabs, however, can be more aggressive, so it is best to allow them plenty of space and extra food when needed.