Their common name, Sea Hare, is derived from their rabbit like appearance as well as their appetite for greens. Sea Hares  are in the order Anaspidea and the family Aplysiidaeare and are generally referred to as sea slugs.  There are many beautiful sea slugs which are not recommended for the aquarium as their dietary needs are either unknown or extremely difficult to replicate in captivity.  Sea Hares however are entirely herbivorous  There is one in particular, Dolabella Auricularia, that thrives in captivity and rapidly consumes hair algae.

Sea Hare

Sea Hare - Dolabella Auricularia

In an effort to test the Sea Hares reputation we placed one into a tank that was overcome with hair algae.  Anyone who has been in the saltwater hobby has one time or another accidentally introduced hair algae either on liverock or coral.  Hair algae as you know is extremly efficient at absorbing nutrients and regardless of your water quality the same conditions that make for a healthy environment for corals also provide algae with what it needs to grow.

Before Adding The Sea Hare

Before Adding The Sea Hare

If you have tried other options unsuccessfully take a look at the results of adding a Sea Hare.  It only took about 5 minutes for the Sea Hare to begin clearing the rocks and substrate.  We did notice that they prefer to stay near the substrate so you may want to lay a few pieces of liverock close to the bottom if you don’t see the Sea Hare reaching the top of the tank.

By the next morning virtually 1/5 of this 50 gallon tank was completely cleared of hair algae.  We do recommend adding some Trochus Snails as well to clean up behind the Sea Hare.  Think of the Sea Hare as a weed eater and your snails as the lawn mower.  They clean up what is missed.  The Sea Hare unlike a lot of other cleanup options will consume hair algae regardless of the length.  So don’t worry if you have algae over an inch long.

Here is a picture of the same tank 3 weeks later.  You will notice that many different kinds of Caulerpa are now thriving as they are no longer choked out by the hair algae.

After Adding The Sea Hare

After Adding The Sea Hare

The Sea Hare does not like a lot of currents so we recommend turning off your pumps at night which is when the Sea Hare will come out to feed (Except at first if they have been at the local fish store without food).

Their dietary needs are important to consider. They have a voracious appetite so we recommend planning ahead to either feed alternative algae fair once your tank is clear or to share your Sea Hare with other aquarists.  We have been feeding the Sea Hare a supplemental diet of Sally’s Seaweed Salad- Green Marine Algae, which he appears to really enjoy.

Our Disclaimer:

Over the years we have heard about their remarkable abilities but we have avoided them as there is a potential for Sea Hares to ink.  This ink is toxic, however there are varying accounts of the degree of toxicity. We have avoided purchasing Sea Hares in the past due to this potential.  However, by acclimating the Sea Hare slowly, providing high water quality and powerful filtration we feel this threat can be greatly reduced. Make sure you find a way to cover pump intakes as that is most likely going to be the biggest threat to your Sea Hare.

There are currently multiple locations which breed Sea Hares in captivity, however it is done so for medical research instead of for the aquarium hobby.  Scientists are currently studying Sea Hares brains which are a clump of nerve cells in an effort to understand more about our brains.

If you have experience with Sea Hares, please feel free to add to this article.