Skip to content Skip to footer

Assassin Snail: Characteristics, Diet, Facts & More [Fact Sheet]

There are many aquatic creatures that inspire awe and fascination, but few are as intriguing as the Assassin Snail. This tiny creature with a rather ominous name is a favorite among freshwater aquarium enthusiasts for its unique characteristics and behavior.

This article dives into the captivating world of the Assassin Snail, from its intriguing biology to its critical role in the aquatic ecosystem.

The Assassin Snail at a Glance


Phylum:Mollusca (Mollusks)
Species:Clea helena

Essential Information

Average Size:0.75-1 inch (1.9-2.5 cm)
Average Weight:A few grams
Average Lifespan:2-3 years
Geographical Range:Southeastern Asia
Conservation Status:Not evaluated

Species and Subspecies

The Assassin Snail, scientifically known as Clea helena, but also as Anentoma helena, is one of several species in the Clea genus. However, it’s the most well-known and commonly kept in aquariums.

Differences between species in this genus primarily come down to geographical distribution, size, and shell characteristics, with C. helena being recognized for its distinctive yellow and dark brown, almost black, striped shell.



The Assassin Snail is a small and beautifully marked creature. It typically reaches a size of about 0.75 to 1 inch (1.9 to 2.5 cm) at full maturity. Its shell has a conical shape with a yellowish base color and darker brown spiraling stripes, giving it a striking appearance. The body of the snail is greyish and can be seen when the snail extends from its shell.

There is no noticeable sexual dimorphism in the Assassin Snail, meaning males and females appear very similar and it can be challenging to differentiate them just by looking.

Habitat and Distribution

The Assassin Snail is native to Southeast Asia, with populations found in Malaysia, Thailand, and Indonesia. They inhabit freshwater habitats, specifically slow-moving and calm bodies of water. They are usually found in places with sandy or muddy substrates where they can easily burrow.

In the wild, these snails can be found in warm climates. However, they have been introduced worldwide through the aquarium trade and are kept in freshwater aquariums under a variety of conditions.

Assassin snail closeup


Assassin Snails are known for their predatory behavior and are primarily nocturnal, becoming most active during the late evening and night. They can, however, occasionally be seen during daylight hours, particularly if the aquarium lights are dim or if they are very hungry. While they are not social creatures that live in packs or herds, they are not territorial and will cohabit peacefully with others of their kind.

These snails are great burrowers, often burying themselves in the substrate with only their proboscis and eyes visible. They don’t communicate in the traditional sense of creating sounds or signals, but they will react to the presence of food or potential mates in their vicinity.

Diet and Hunting/Feeding Behavior

Assassin Snails are carnivores, and they have a reputation for being able to help control populations of other snail species in aquariums, hence their name.

They are particularly fond of pest snails like bladder snails, ramshorn snails, and Malaysian trumpet snails. Aside from snails, they also eat other protein-based foods, including dead fish, worms, and uneaten protein-heavy fish food.

In terms of hunting behavior, Assassin Snails track their prey using chemical cues in the water. Once they’ve located their target, they will pursue it, often burrowing and following the snail until they can catch it. Then, they use a specialized appendage called a proboscis to consume the soft parts of their prey.


In the wild, Assassin Snails can fall prey to a variety of animals, including birds, amphibians, and fish. Larger snail species may also prey on them. In an aquarium setting, they are generally safe unless housed with large, aggressive fish species.

Their hard shells provide them with a good deal of protection from potential threats, but they are still vulnerable when they expose their softer body to eat or move around.

Clea helena shell

Reproduction and Life Cycle

Assassin Snails have a fascinating reproductive cycle. Unlike some snails that can reproduce asexually, these snails are gonochoristic, meaning there are distinct male and female individuals that mate sexually. During mating, the male attaches to the female, and copulation can last for several hours.

After mating, the female Assassin Snail will lay her eggs individually, usually deposited on hard surfaces such as aquarium glass or decorations. The egg is encased in a small, transparent casing. The gestation period for each egg is about a month, depending on temperature and water conditions.

Each egg hatches into a tiny, fully formed snail. The number of offspring produced can vary widely, and a single female can produce several eggs after a single mating session. There is no parental care provided to the young; once the eggs are laid, they are left on their own to hatch and grow.

Conservation and Threats

As of now, there is no specific conservation status for Assassin Snails. They are not currently listed as endangered or threatened. However, as with many freshwater species, changes in their natural habitat due to pollution, habitat destruction, or climate change could pose threats in the future.

In terms of conservation efforts, keeping Assassin Snails in home aquariums may contribute to their propagation. However, it’s essential to avoid releasing these snails into non-native waters, as they can become invasive and disrupt local ecosystems.

It is also important to support broader environmental conservation initiatives that protect freshwater habitats, as this is beneficial to Assassin Snails and countless other species. Ethical sourcing of these snails for the aquarium trade, by purchasing from responsible breeders rather than those who capture wild specimens, can also help maintain wild populations.

Fun Facts

  1. The Assassin Snail’s name might sound menacing, but it’s derived from its carnivorous diet. These snails feed on other snails, hence the name “Assassin.”
  2. Despite their carnivorous diet, Assassin Snails are peaceful with tank mates of other species that are too big to eat. So you’ll often see them happily cohabiting with fish and shrimp.
  3. Assassin Snails are quite slow movers. It might take them a while to find their prey, but once they do, they are very effective hunters.
  4. Assassin Snails are native to Southeast Asia, particularly Malaysia, Thailand, and Indonesia. Despite this tropical origin, they have become popular in freshwater aquariums around the world.
  5. While many aquarium owners use chemicals or other methods to control pest snails, the Assassin Snail is a natural solution. A few Assassin Snails in a tank can help keep populations of unwanted snails under control.

Frequently Asked Questions

Can Assassin Snails live with other snails?

Yes and no. Assassin Snails are generally peaceful with other tank mates but are known to eat other smaller snails. Therefore, it’s not recommended to house them with other snails you’d like to keep.

How long do Assassin Snails live?

With proper care, Assassin Snails can live up to 3 years. However, their lifespan can be influenced by factors such as diet, water quality, and temperature.

Can Assassin Snails reproduce in freshwater aquariums?

Yes, Assassin Snails can reproduce in freshwater aquariums. They lay individual eggs that, after about a month, hatch into fully formed, tiny snails.

How many Assassin Snails should I keep in my aquarium?

The number of Assassin Snails you should keep depends on the size of your aquarium and the presence of other species. However, a good general rule is to keep around 1 snail for every 5 gallons of water to prevent overcrowding.

What do Assassin Snails eat?

Assassin Snails are carnivorous and feed primarily on other snails and worms. In an aquarium, they can also eat sinking carnivore pellets, fish flakes, and frozen or live protein-based foods. They might also scavenge for uneaten food or decaying plant matter.

Top image: Wikimedia Commons

Leave a Comment