Stomatella Snail – Are They Good or Bad for Your Reef Tank?

These snails are hitchhikers that often come in on live rocks. They are less than one inch long and have what are referred to as fingernail shells that only cover half of their bodies: that’s why they can look like a slug.

Are Stomatella snails good or bad for your reef tank?

These fellas are good for your reef tank and breed easily. Watch them move in the moonlight because these guys are nocturnal. They will eat your algae and help keep your tank clean. Read on for more about stomatella.

What are stomatella snails?

These are the good guys to have in your saltwater reef tank. You can identify these guys because they look sort of like a slug or snail with a half shell. They are usually 2.5 cm in length and can be found in many colors including black, white, green, brown, red, pink, and orange.

What do these snails eat?

They eat the algae in your tank and will help to keep levels of unwanted algae under control. They are mainly active at night, which is the best time to watch them. 

They can even lose their foot and grow it back, as a lizard does with its tail. The foot spins to distract a predator while the snail gets away.

You may find a stomatella on some live rock that you buy for your tank. Keep it! These guys are beneficial and their populations do not grow excessively. If they do, you can even sell them as a breeder. There truly is no downside to keeping these because they are reef-safe.

Six Line Wrasses, Four Line Wrasses, tuskfish, and Peppermint Shrimp are natural predators to these snails and will quickly eat them if given the chance. Try not to have these guys in the same tank as those predators.

Caring for Stomatella

Stomatella are a great addition to any saltwater reef tank. They will feed on microalgae and reproduce readily. Keep your tank water clean and watch them flourish. You can watch these fast snails move at night with a flashlight.

How to keep them

What do they need in a tank? These snails require your tank to be in a low nitrate environment with stable calcium and magnesium levels. Do not use copper medication in your tank.

Your water should be kept clean and if possible have some algae present. If you cannot stand having algae in your reef tank, then these guys can eat dried seaweed (Nori) instead. They may also eat leftover flaked food.

You should not have more than five of these snails per 20 gallons of water. We recommend one per every five gallons.

They can be sensitive to changes in specific gravity, which means you need to give these little guys extra care when you hope to introduce them to your tank.

You will need to acclimate them to your tank. Drip acclimate them for twice as long as you would with a fish. Place them in your tank on a rock because they would rather be on a hard surface than sand. If the snail has not moved in a few days, keep an eye on it and consider removing it.

Stomatella snail spawning

Stomatella spawn readily in aquariums and saltwater reef tanks. You can count on seeing some tinier slugs after a while of having more than one stomatella.

These snails will all spawn at the same time. During the day they will migrate to a higher part of the tank. They will then release their egg and milt into the water, where it will combine. This might make the water look cloudy, but it will clear up quickly.

The eggs and milt are sometimes eaten by fish and filter feeders, but this should not greatly affect the population.


When your stomatella breed, you will find small dots no larger than pinpricks that are your new baby stomatella. They will be high up on your tank glass near where your stomatella were hanging out to release the egg and milt.

These look like a trail of snail eggs, small dots that will start to move around on the tank glass when they mature enough. Within a month, they will look like stomatellas.

What eats stomatella snail eggs?

Some of these eggs may be eaten by filter feeders and predators, but once they develop their fingernail-like shells they should be out of trouble and able to more readily protect themselves.

Breeding – stomatella snail reproduction

While many creatures can breed asexually, it takes more than one to multiply stomatella. They will breed depending on the moon cycles. Watch for them to move up higher in your tank and stay there for at least two days. Afterward, you should see the snail egg trail.

If you find yourself overrun with these guys, you don’t need to worry. You can easily sell off some of your snails without hurting your snail population. Reach out to your local reef club to offer them up: someone is sure to be wanting some of these algae eaters.

You can harvest them easily from the glass without causing harm to the little fellas. Simply use a tool to scrape them off of the glass and into another container so you can begin the process of drip acclimating them into a separate tank. It is best to do so before they grow to adult size.

Make sure to maintain your tank at the same clean and stable water levels as mentioned previously. You can feed your stomatella with microalgae or dry seaweed (Nori).

Where can I find stomatella?

These creatures are sensitive and they cling tight to their substrate, which is why they are not readily sold. They can be easily removed from glass but not from rock.

They cling to their limpet or abalone and can lose their foot if you attempt to remove them. These guys are nicknamed paper shell snails or fingernail snails because of their small shells which are difficult to grab onto. It can be lethal to remove them from their perch.

You most often find these snails as hitchhikers on a live rock that you purchase for your reef tank. Look for them in your next shipment of live rock or contact your local reef club to ask someone for any extras you can purchase for your own tank. You may also be able to check eBay, but it would be best to refer to your local reef tank club first.