Hermit Crabs and Snails Work as Reef Tank Janitors

Blue legged hermit crab

Hermit crabs and snails are often the first janitors that aquarists introduce to their aquariums since they are excellent at managing typical algae issues.

About Hermit Crabs

Phylum Arthropoda
Subphylum Crustacea
Class Malacostraca

Hermit crabs are scavengers, in case you didn't know. Yes, most animals will consume almost everything they can get their hands on. As a result, if you pick a Reef Safe Hermit Crab, they make excellent cleaners for a reef tank.

Hermit crabs that are properly picked should have no detrimental influence on a reef environment. They are, in fact, entirely useful. Small species that don't become much bigger than a couple of inches are the best since they don't bother other tank inhabitants and can get into tiny cracks and crevices where algae grows that larger hermits can't. They may also reach areas beneath rocks and corals where rubbish or debris has gathered in order to clear it.

Large species like the Anemone Carrying Hermit (Dardanus pedunculatus), Yellow Hairy Hermit (Aniculus maximus), and Halloween Hermit (Trizopagurus strigatus) should not be used as reef janitors since they might harm your reef. These hermits may cause tank life to be disrupted by climbing on everything and, due to their enormous awkward, thick shells, collapsing rockscape arrangements and shifting corals. They may also fight or eat other tank residents. If you want to raise giant hermit crabs, make sure you have a tank with the right atmosphere and size, and bear in mind that they will outgrow their shells. As they molt and develop, you must give them with new housing (bigger shells), otherwise they may assault other shelled animals in order to obtain a new shell. Clibanarius vittatus, sometimes known as the Striped Hermit Crab, is a widely imported species with this feature. Do your hermit(s) require shells? Here are a few companies to look into.

Popular Algae Eating Hermit Crabs

  • Small hermit crabs of the Genus Calcinus found in Hawaii are extremely efficient little critters. 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. Because of their tiny size, these hermit crabs can really get into those small spaces in a reef tank that other hermits cannot. The Left-Handed or Dwarf Zebra Hermit Crab is one of the best examples of a great reef safe algae eater.
  • The Blue Legged Hermit (Clibanarius tricolor), as well as other similar species are quite popular, but some such as the Anomura sp. will kill Astraea snails to obtain their shells.
  • The Red Legged Hermit (Clibanarius digueti) is said by some to be a much better algae eater than the Blue Legged Hermit, less aggressive, and has been reported to eat red slime algae.
  • Aside from eating algae, the golf ball sized Blue Eyed Hermit Crab (Paguristes erythrops) spends its time stirring up the top layer of the substrate of the aquarium.
  • The Scarlet Hermit Crab (Paguristes cadenanti) is one of the most popular hermits with reef keepers, because of its colorful appearance, and because it will eat all kinds of algae, such as red, green and brown slimes, as well as .

About Snails

First and foremost, learn how to recognize and avoid any predatory shelled snails. These are stinging, poisonous creatures that devour their prey whole or kill them with venom, generally injected with a harpoon. The biggest and most visible of the poisonous species are all members of the genus Conus, whose venom is harmful not only to other marine life but even to people! Predatory snails are rarely sold in fish stores, although they can occasionally be seen hitchhiking with live stones obtained in the wild.

The Astraea/Astrea, Turban/Turbo, and Trochus/Trocus are three of the most popular marine snail species used for algae management in saltwater aquariums and reef tanks, with various variants found worldwide. Let's look at each of these groupings in more detail.

  • According to Julian Sprung's Reef Aquarium Manual, Volume One, Astraea sp. are the ideal snail to be placed in your aquarium as soon as ammonia and nitrite levels reach acceptable levels (less than 1 ppm). Introduced as soon as possible to a new aquarium, that has reached this cycling phase, these snails effectively limit the development of all microalgae. In other words, they are good at eating diatoms but will consume Red Slime and  algae as well. The Astraea tecta found in Florida and Caribbean waters inhabits rocky intertidal regions and is said to be quite adept at removing algae from rock surfaces.
  • There are numerous species of Turbans, referred to as Turbo Snails, and Trochus snails worldwide that feed solely on algae, making them perfect candidates for . These types of snails are less adept at dealing with irregular surfaces, so they usually divide their time between cleaning the glass and digging in the sand for detritus.
  • Another good glass polisher is the tiny Black Nerite (Pipipi) snail (Nerita picea) found in Hawaii. It only reaches a size of about 1.5 cm and spends its time living along the shallow rocky and coral rubble covered inter tidal regions of the shoreline, in cohabitation with small hermit crabs of Genus Caleinus. The N. picea likes to reside on the aquarium glass in search of algae to eat during night time hours but will spend some time roaming around to aquarium. Close relatives are N. neglectus, that grows to the size of a thumbnail, and N. polita lives in the sand during daylight hours and grows to about 1-1/2 inches. These two species like to crawl out of the aquarium, therefore, they are not good choices.