Are Fighting Hermit Crabs Good for Reef Aquariums?

While there is no specific species of hermit crab known as a "fighting hermit crab," hermit crabs engage in territory battles on occasion. Most often, these fights are instigated when a hermit crab outgrows its shell and seeks another shell. If another hermit crab occupies the shell, a fight ensues. Despite this aggressive behavior toward one another, several species of hermit crabs do well in reef aquariums.

  1. Omnivores

    • Hermit crabs are, by nature, omnivores. This means they eat both animal and plant life. They are also notorious scavengers and will eat just about any organic material they find as they move along the bottom of a reef aquarium. Along with eating some of the waste products produced by fish within the reef aquarium, hermit crabs also devour many kinds of unsightly algae, making them ideal candidates for display tanks.

    Conditions

    • One important aspect to consider when putting hermit crabs into a reef aquarium is the size of the tank and the quantity of the crabs. Hermit crabs are territorial. If too many hermit crabs find themselves in tight quarters, they will fight for territory and upset the environment of the reef aquarium. Make sure there are sufficient shells for the crabs to grow into as well. Too few shells will also lead to fighting when the time comes for the hermit crabs to find new quarters.

    Color

    • There are several colorful varieties of hermit crabs to add to reef aquariums. There is the scarlet hermit crab, which is an excellent reef cleaner as well as having a vibrant scarlet coloration; the blue-legged hermit crab; and the green emerald hermit crab. All three of these varieties provide adequate scavenger cleaning for the reef aquarium while also providing colorful displays for the tank. In addition, the emerald green hermit crab is one of the few crabs that actually cleans up bubble algae, which is one of the most troublesome algae found in reef aquariums.

    Symbiotic Relationships

    • Hermit crabs in reefs form symbiotic relationships with some of the life forms sharing their tank. One amazing example is the anemone-carrying hermit crab, which actually has an anemone attached to its shell. When the time comes for the hermit crab to find a new shell, it will either attach the old anemone to the new shell or it will find a larger anemone to suit its needs. This particular hermit crab tends to be on the more aggressive side, however, and does best in a large reef aquarium with low lighting levels.