Black Devil Snails (AKA Lava Snails) and Bettas

Bettas make ideal companions for many different snails, and Black Devil Snails are no exception.

As a biologist specializing in aquatic invertebrates, I’ve studied black devil snails, or lava snails, in detail. These fascinating snails have special care needs, but the information I’ll share below will help you keep them and betta fish together.

In this care guide, I’ll discuss essential aspects, like their water preferences, diets, and appearance. Whether you want to learn how to take care of your Lava Snails, or are thinking about getting some, you’re in the right place.

Black Devil Snails (Lava Snails) Natural Habitat And Origin

Faunus ater snails, also known as black devil snails or lava snails, may live in either fresh or slightly brackish water, like estuaries and coastal lagoons.

Studies indicate that these snails are more common in areas with brackish water and a greater tidal influence. They live in substrates like sand, mud, and rocks, where they feed on detritus and organisms in the environment. These animals can form large aggregations in certain regions, especially during the breeding season.

Lava snails are found in diverse localities, such as the west coast of India, the island of Java, Sumatra, New Guinea, and the Philippines. 

by H. Zell (CC BY-SA 3.0)

In Java, they inhabit brackish waters close to the coast, streams, small rivers, and lagoons. Museum records show they may also be seen in large numbers in Lake Cayangan, in the Philippines, at depths of 1 to 1.5 meters living in substrates such as sand and rock.

Despite their wide geographic distribution, we know little about these snails in their natural environment.

Because they are considered a delicacy in some regions, Faunus ater snails are collected in large quantities for human consumption.

Black Devil Snails Appearance 

Black devil snails may reach up to 9 cm in length. They’re generally dark in color, with a dark brown or black shell and a rough, opaque surface. The elongated, spiral-shaped shell surface is covered by a thick dark periostracum that protects them from the acidic environment in which they live. 

They have light-colored heads ranging from white to light yellow, with eyes located at the base of the upper tentacles. The short, stout tentacles are similar in color to the head. The large, muscular foot is usually dark in color. 

The black devil snail has a large, muscular mouth with strong, robust radula that they use to feed on thicker types of algae and other tough foods. 

by Mário NET (CC BY-SA 4.0)

Furthermore, it is interesting to note that black devil snails can be found covered in egg masses of Neritina, another type of snail, and those living in brackish waters with oysters attached to their shells.

Their appearance may vary slightly between individuals and between populations, depending on environmental and geographic conditions. For example, the shell can be smoother or rougher depending on the substrate the snail lives on.

Black Devil Snails (Lava Snails) Taxonomy

The black devil snail, Faunus ater, belongs to the family Pachychilidae. This family of snails is easily recognized by their large, thick shells, with an ovoid opening and a well-developed spiral. In addition, the Pachychilidae have a horny operculum and a short, wide siphon.

People often confuse it with Melanoides tuberculata, a freshwater snail in the family Thiaridae. However, there are some notable differences between the two.

Melanoides tuberculata has the following characteristics:

  • Melanoides tuberculata usually does not exceed 3 cm
  • The shell of Melanoides tuberculata is lighter and less shiny
  • The shell of Melanoides tuberculata is more elongated
  • These snails have smaller feet

Black Devil Snails have these characteristics instead:

  • Lava snails can grow to around 9 cm in length
  • Black devil snails have a darker and shiny shell
  • Lava snails have a wider, more rounded shell
  • Black devil snails have a thicker rim and a more pronounced whorl on the shell
  • The foot is wider and flatter in Faunus ater.

Although Faunus ater and Melanoides snails may look similar at first glance, they have distinct taxonomic features that set them apart. 

How Do Black Devil Snails (Lava Snails) Behave?

Black devil snails are exquisite, quirky creatures that rarely (if ever) show aggression. This makes them a great addition to community tanks and ideal for beginner aquarists. 

They’re nocturnal animals and usually spend the day buried in the aquarium substrate or hidden under decorations. 

While they’re great cleaners, these snails burrow into the aquarium substrate, which can cause problems for some plants.

Black devil snails aren’t skilled climbers and rarely make it out of the aquarium.

Other important considerations when caring for these snails include ensuring that the tank is well-lit and there are enough plants and decorations for them to hide in. 

How To Set Up Your Tank For Black Devil Snails (Lava Snails)

Here are some important considerations when setting up your aquarium for lava snails:


Since these snails like to hide, I’d recommend adding suitable plants to provide hiding places. Broadleaf plants like Anubias and Echinodorus are great for this. Also, ensure that the plants you choose are non-toxic, as the snails may nibble at them.


Black devil snails like to burrow into the aquarium substrate. Round gravel or fine sand is an ideal substrate for these snails, as it allows them to burrow easily. Avoid using rough, sharp, or stony substrates; these can damage the shells of these animals.

Water parameters

Black devil snails prefer soft, slightly acidic water. Ideal water parameters for these animals include a pH of 7.0 to 8.5 and a hardness of 5 to 15 dKH. It’s also vital to keep the water temperature between 72°F and 84°F  (22℃ and 29℃).

Black Devil Snails (Lava Snails) Diet In The Wild And Diet In An Aquarium.

Black devil snails (AKA lava snails) are omnivorous, eating a diverse diet in the wild. Wild snails mainly feed on algae and plant debris, but may also eat small invertebrates and dead animals.

In captivity, they’ll enjoy a diverse diet, including items like:

  • seaweed flakes
  • fish wafers
  • fresh vegetables like squash, zucchini, and spinach 

It’s worth mentioning that they’ll also eat food scraps and other aquarium debris. If well-fed, these snails will rarely eat live plants in the aquarium.

Despite being known to be algae eaters, some breeders don’t consider them efficient control for these plants. Either way, they’re a great option for planted aquariums.

You should monitor their feeding to avoid overfeeding them. If you feed them too much, it can result in excess detritus in the aquarium, which can negatively affect water quality.

How Do Black Devil Snails (Lava Snails) Reproduce In A Fish Tank? Can They Cause Snail Overpopulation?

Black devil snails are oviparous (have separate males and females). So far, it is believed that they can’t reproduce in aquariums, likely because their larvae and eggs may need brackish water to develop. 

We know little about their reproductive process, but it’s extremely unlikely that black devil snails will overpopulate your aquarium.

by Mário NET (CC BY-SA 4.0)

Black Devil Snails Compatibility With Betta Fish

Lava snails are generally peaceful and get along with most peaceful animals. Particularly, they make excellent companions for bettas. Since they fill different niches in the water column, your bettas will probably rarely interact with the snails.

However, as with any animal, not all bettas share the same temperament. If you decide to keep black devil snails in a Betta aquarium, monitor them carefully at the beginning to ensure that there are no conflicts. If you notice your Betta attacking the snails, you may need to remove them from the tank.

Where Or How Do You Get Them?

Black devil snails are available at many pet stores, online specialty websites, and aquatic specialists.

When buying online, check the slugs are shipped in safe, healthy conditions with proper packaging and temperature control.

If you decide to purchase black devil snails in person, choose healthy individuals and check them for signs of illness or injury. 

Black Devil Snail Fun Facts

  • In some regions, Black devil snails, Faunus ater, are consumed as food.
  • 1982 saw the first record of the species in the Americas, in Nicaragua. 
  • These snails are also used in traditional Chinese medicine to treat various ailments.
  • Although they’re called black devil snails, their coloration can vary from reddish-brown to blue-black, depending on environmental conditions.
  • Young snails have black shells that turn mahogany when they become sexually mature.
  • Sometimes these snails carry oysters, or the eggs of other snails, attached to their shells.


Black devil snails will make an exciting addition to your betta’s aquarium. Even kept on their own, these are fascinating creatures that make great contributions by controlling algae.

As long as you meet their basic needs, as listed in this guide, your snails will be around for quite some time.

About the author

Hi, I am Marcelo.

I am fascinated with researching and writing about fish.
I have a degree in biology (herpetologist) and animal science (zootechnics) specializing in ornamental fish and South American biotopes.

You can find the articles I wrote here.

About the author

Hi, I’m Johanan! I love animals of all shapes and sizes, but especially fish. I’ve gone from working at a pet store as a teenager to keeping and breeding Bettas and other fish at home. My passion for fish is endless!

You can find my articles here.

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