Lettuce Nudibranch or Lettuce Sea Slugs are incredibly underrated tank additions. There are no other species that are more unique, beautiful, and capable of some astonishing things than the Lettuce Nudibranch. They not only add a unique look to the tank but also help rid the tank of some of the more aggressive and vigorous forms of algae. 

Elysia crispata is a form of sea slug but is also knows as the Lettuce Nudibranch because of the function they perform within saltwater tanks. Like the nudibranchs, they help rid the tank of algae by voraciously consuming it throughout the day. 

Function and Diet 

They belong to a category of creatures broadly classified as sarcoglassans. What makes them unique is their ability to absorb the chlorophyll from the plant and algae matter they consume into their tissue. This allows them to generate their own energy in the presence of sunlight through a process called kleptoplasty. But, it also gives them a stunning green tinge to the curly furls on top of their slender body. This gives them a distinct appearance.

They broadly consume all forms of algae but their favorites include hair and bubble algae. Both these types of algae is a pain for aquarium hobbyists because they are very aggressive. Even after Fluconozole treatments, they tend to return quickly and take over the tank, depleting oxygen and nitrogen for the fish and reefs.

By consuming these rarer but harder-to-get-rid-of algae, they perform a crucial function in certain tank setups. They also consume more algae than other ‘tank-cleaners’ like the hermit crabs and snails. This makes them the pound for pound champion of algae destruction!

They also might consume some other plant matter, but this is rare behavior and there should be plenty of algae for them to consume. If you think that your tank has very low quantities of algae (observe rocks for greenish tinge or slimy texture), you might want to supplement this with some frozen algae in small quantities. This will ensure that your lettuce nudibranchs have plenty to graze on.


The Lettuce Nudibranch is very sensitive to strong currents in the tank. Their lack of limbs makes them easy to displace in tanks with strong filters or electronic current generators. They tend to occupy shallow ocean pools where currents aren’t so severe.

Make sure you have screens on your filters if you decide to introduce Lettuce Nudibranch into your saltwater tank. Also, try and use non-electronic wave generators to keep rotating the nutrients instead of a high-power electronic pump.

Having aggressive or highly curious species of fish also might be detrimental to the Lettuce Nudibranch because of their appearance. The more aggressive fish species tend to peck and nibble at them, creating a highly stressful environment for the grazers.

However, this shouldn’t cause too much of a concern because the lettuce nudibranch does well in most aquarium setups. They tend to find tiny crevices and spaces and spend most of their time feeding while being almost still.

The Lettuce Nudibranch, like most invertebrates in the ocean, are very sensitive creatures that react to minute changes in their environment. This makes it extremely crucial for you to acclimatize them slowly into their new saltwater tank. The breeder or vendor might have water of different pH and mineral densities. To make sure they will thrive in your tank water, slowly introduce them to their new environment in incremental time periods. Also, make sure to test your water for Copper concentration as it is a deadly metal to lettuce nudibranchs. 

But, fret not. They are very robust creatures once you follow a few easy rules. You will have a unique creature with varying colors and a wavy, hypnotic pattern to observe for many years. They also help keep your tank clean and maintain a wholesome environment for all creatures in your tank.