Sea Hare Tank Requirements

Little about the sea hare is rabbitlike. It's a variety of marine slug, native to coral reefs in waters around the world. The silhouette of its eye stalks bears a slight resemblance to that of a rabbit's ears, hence the name. The sea hare's appetite for algae makes it appealing to owners of saltwater tanks, but it's best left to expert aquarists.

  1. Capacity

    • The sea hare is a large snail, beginning at 3 or 4 inches but capable of growing to a foot in length. They're not recommended for aquariums smaller than 75 gallons, because they don't tolerate low water quality very well; larger tanks fluctuate less in water quality. Sea hares also release defensive toxins into the water if they feel threatened. In a larger tank, it's less likely that one of your tank's other inhabitants will get close enough to the sea hare to trigger this defensive reaction accidentally.

    Toxin

    • The toxin released by sea hares is potent enough to cause high mortality among aquarium fish. You'll need a good chemical filter on your tank to remove it quickly before it can do too much harm. A larger tank also provides a margin of safety by diluting the toxins. Never introduce a sea hare into a tank containing any aggressive species, which is almost certain to result in a discharge of toxins. You'll also need to fit a protective cover over the filter intake, because the sea hare will also feel threatened and release its toxin if it gets sucked into the intake.

    Habitat

    • Sea hares like open spaces to move around in, preferably with sand or coral rubble at the bottom. Live rock or living corals, to attract the algae it feeds on, are also useful to have in the tank. In their natural reef environment the snails favor shaded, grassy areas, so it's good to replicate this in your tank if possible. Shade the tank's lights in one area to give the sea hare a comfortable resting place.

    Diet

    • The sea hare's natural diet is green algae of the Caulerpa family, especially hair algae. It will take a surprisingly short time for one snail to clean all the algae from a tank, so ongoing feeding usually involves providing a substitute. Algae pellets are available from pet stores, but sea hares are perfectly happy to eat nori, the seaweed used for wrapping sushi, from the Asian section of your supermarket. Another option is to "time share" your sea hare with two or three other hobbyists, allowing it to clean each tank in turn for a few weeks.