The Assassin Snail (Clea helena)

Assassin snail.

Assassin snails (Clea helena) are a type of freshwater snail that is highly sought after by aquarium hobbyists because of their ability to prey on pest snails in aquariums. They are relatively easy to care for and can thrive in various aquarium setups.


The common name “Assassin snail” is derived from the snail’s predatory behavior of preying on and killing other snails. This trait is quite helpful in removing unwanted snails, especially in planted tanks.

Natural Habitat

Assassin snails are native to Southeast Asia and found in various types of freshwater habitats. They are most commonly found in slow-moving or stagnant bodies of water with a soft substrate, such as mud or sand, like rivers, streams, and rice paddies.

Assassin snails have been widely introduced to other parts of the world, including Europe and North America, primarily because of their popularity in the aquarium trade. As a result, they are considered an invasive species in some regions, where their predatory behavior can significantly impact native snail populations.


Assassin snail.

Assassin snails are tiny. They have a conical-shaped shell reaching up to an inch or 2.5 cm long. The shell is typically yellowish-brown with dark brown stripes that run perpendicular to the whorls of the shell.

The snail’s body is elongated and tapers to a point at one end, which is used to extend and retract its foot. The foot is used for movement and can be seen protruding from the snail’s shell as it moves around the aquarium. The snail has two sensory tentacles on its head, which detect food and other snails in its environment. 

It also has a siphon-like structure called a proboscis, which it uses to hunt and feed on other snails.

Tank conditions

Assassin snails are relatively easy to care for and can adapt to many different setups, but there are a few key factors to consider to ensure that they stay healthy and happy.

  • Tank Size: 10 gallons or more
  • Water Parameters: Slightly alkaline water with a pH between 7.0 and 8.0, temperature between 72°F-80°F (22°C-27°C), and water hardness between 8-12 dKH.
  • Good filtration and regular water changes
  • Substrate: Soft substrates, such as sand, as they like to burrow into the substrate during the day.
  • Decorations: To provide hiding spots and shelter


Assassin snails are carnivorous and primarily feed on other small snails. They are known for controlling snail populations in aquariums, making them a popular choice for hobbyists looking to manage snail overgrowth. Assassin snails may also consume other small invertebrates, such as crustaceans, worms, and insect larvae.

In an aquarium setting, Assassin snails can be fed a variety of foods, including sinking pellets, frozen or live bloodworms, brine shrimp, and other small meaty foods.

Assassin snails are generally opportunistic feeders and scavenge for food throughout the tank. However, they are most active at night and may prefer to feed on snails.

Temperament And Good Tank Mates

Apistogramma & Assassin snail.

Assassin snails are generally considered to be peaceful and relatively docile in temperament. However, they will predate on smaller snails and invertebrates.

Ideal tankmates for the Assassin snail include

  • Freshwater shrimp that are larger than the Assassin snail
  • Small fish like Tetras, Corydoras, and Otocinclus catfish
  • Other snails that are of similar size


Assassin snails are among the more difficult invertebrates to breed. Putting together multiple snails will lead to at least a few pairing up. Once a pair has formed, they will mate regularly and lay eggs. The eggs should be moved to a nursery tank to ensure maximum viability.


Assassin snails are generally hardy and resistant to many common aquarium diseases. However, like all aquarium inhabitants, they are not immune to illness and can contract infections. Good water conditions and a proper diet will keep most of these infections at bay.

If these snails need to be treated for a disease, the medication used should be safe for invertebrates like snails.

Closing Remarks

Assassin snails are prized for their ability to control unwanted snail populations. They have an interesting appearance as well. They are an interesting and beneficial addition to many freshwater aquariums.

Common NameAssassin snails
Scientific NameClea helena
Care LevelEasy
TemperamentPredate smaller snails and invertebrates but docile towards other inhabitants
TankmatesOther invertebrates that are of same size or largerPeaceful fish
DietSmaller snails, sinking pellets
Size1 inch or 2.5 cm
LifespanAbout 2-3 years

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