If you have ever been to the beach for a vacation, you have likely seen small displays in seaside stores selling hermit crabs. These creatures are unique in that they live their entire lives in shells – but they are not confined to them. In fact, hermit crabs do not grow their own shell – they actually move to different shells as they grow. This fact alone makes hermit crabs a very interesting pet but it is not the reason they have become so popular in reef tanks. Hermit crabs make excellent reef tank inhabitants because they serve in the role of a cleanup crew.
Basics About Hermit Crabs
Hermit crabs are a type of crustacean and they are more closely related to lobsters than they are to true crabs. These creatures have the iconic crablike legs and claws, but the rest of their body is soft and curved – this is why they need a shell to protect themselves from predators. Because these crabs do not grow their own shells (like snails do), they must use abandoned shells they find in shallow reefs and on the ocean floor. Because they tend to move from shell to shell as they grow, these crabs were given the nickname “hermit crabs.”
There are many different species of hermit crabs but not all of them are recommended for the reef tank. Hermit crabs, for the most part, are excellent reef tank inhabitants because they forage for the kinds of food that fish leave behind – many species eat algae, small snails and detritus in the aquarium – they also help to aerate sand by sifting through it as they feed. Some hermit crabs do eat small fish and even larger fish can become prey if they get too close to the crab. For these reasons, you need to be careful in selecting a hermit crab for your reef tank.
Hermit Crab Tank Needs
Different hermit crabs reach different sizes according to their species but, for the most part, they reach a maximum size around 2 to 2 ½ inches. The ideal water conditions for hermit crabs are similar to most reef tank inhabitants – they prefer a water temperature in the 72 to 78°F range, a pH between 8.1 and 8.4 and a specific gravity (salinity) between 1.023 and 1.025. As long as they have sand to dig through and rock or coral formations in which to hide, your hermit crabs should be happy. Keep in mind, however, that you may have to supplement their diet with dried seaweed or bits of shrimp if there isn’t enough algae for them to feed on.
Like all aquarium inhabitants, the hermit crab requires high water quality and a clean tank in order to thrive. The hermit crab does play the role of a cleanup crew, helping to rid the tank of accumulated waste and algae, but these crabs cannot do all the work alone. In order to keep your tank clean you need to install a high-quality filtration system and make sure to perform your weekly and monthly water changes. Change your filter media once a month and test your tank water weekly to make sure your chemistry levels are within the proper range.
Another simple thing you can do to ensure that your reef tank remains a safe and healthy environment for your hermit crab (and your fish) is to install an EcoBio-Stone. EcoBio-Stones come in a variety of sizes. They are made from natural crushed stone and zeolite. Each EcoBiStone is infused with beneficial bacteria and the nutrients they need to thrive when they are introduced into your tank. Once introduced, the bacteria will multiply and work to maintain the nitrogen cycle in your tank – this is the cycle through which waste products and toxins are removed from the tank. With the help of an EcoBio-Stone, the water in your reef tank will remain clean and clear so your hermit crabs stay healthy.