Assassin Snails

Quick facts

Identity

Also known as

Snail-eating snail

Synonyms

Anentome helena

Environment

Freshwater

Native to

Malaysia, Thailand, Indonesia (Sumatra)

Habitat

Rivers, ponds, lakes, and ditches with soft sandy substrate throughout Southeast Asia; tolerant of stagnant water

Sourcing

Captive-bred

Conservation

Not Evaluated

Care

Care level

Easy

Temperament

Semi-Aggressive

Adult size

0.3 – 1 in (0.6 – 2.5 cm)

Lifespan

1 – 3 yrs

Min tank

5 gal (19 L)

Growth rate

Slow

Placement

Bottom

Water

Temperature

75 – 80 °F (24 – 27 °C)

pH

7.0 – 8.0

GH

8 – 12 dGH

TDS

175 – 250 ppm

dKH

4 – 6 dKH

Flow

Low-Moderate

Behavior & compatibility

Social

Solitary

Aggression to own kind

Low

Active

Night

Invert safe

With caution

Plant safe

Yes

Shrimp safe

With caution

Clean-up role

Pest control, Carrion

Population boom risk

Low

Feeding & breeding

Diet

Carnivore

Foods

Live, Frozen, Pellets, Freeze-dried

Breeding type

Direct development

Breeding difficulty

Moderate

Sexing

Dioecious (separate sexes) but sexes are not visually distinguishable; keep a group to ensure both are present for breeding

Target feeding

Beneficial

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Care guide

Overview

Clea helena is a small predatory snail identified by its yellow-and-brown banded shell, which tapers to a pointed spire. It stays buried in sandy substrate by day, emerging mainly to hunt pest snails or take meaty foods. Best kept in groups in mature, moderately hard water for shell health.

Care

Assassin snails do best in a mature, fully cycled tank with a soft sandy substrate they can burrow into during the day. They are undemanding about décor and will also tolerate fine gravel, though sand lets them display their natural ambush-hunting behavior. Water hardness matters more than most parameters since their shells are calcium-based and will erode in very soft, acidic water, so keep the pH on the higher side and the water moderately hard.

Feeding

In the wild these snails hunt other snail species, and in captivity they will readily clear out pest populations of ramshorn, bladder, pond, and Malaysian trumpet snails. Once pest snails are depleted, offer sinking protein-rich foods such as frozen bloodworm, shrimp pellets, or other meaty foods to keep them fed. They hide in the substrate and emerge mainly when they sense food nearby, often surfacing more actively around feeding time.

Tank mates

Peaceful community fish, shrimp, and plants are generally safe, since assassin snails do not target healthy fish or graze on foliage. Avoid combining them with any snail species you want to keep, including trumpet snails and ramshorns, as these are their preferred prey. Very small or slow shrimp may occasionally be at risk, though established adult shrimp are usually left alone.

Breeding

Breeding occurs sporadically in home aquariums rather than on a predictable schedule, and a group of several individuals improves the odds of having both sexes present. Females lay small individual egg capsules on hard surfaces such as glass, driftwood, or plant leaves, and development is direct with no free-swimming larval stage. Hatching takes roughly seven to eight weeks, and population growth is naturally limited once the supply of prey snails runs low.

Health

These snails are generally hardy in a stable, mature tank and have few specific ailments reported in the hobby. Shell erosion or pitting can develop in soft, acidic, or mineral-poor water, so maintaining adequate hardness helps prevent this. Sudden parameter swings or copper-based medications used to treat fish should be avoided, as invertebrates are sensitive to copper.

Sources

1. Caresheet: Assassin Snail | Clea Helena - Aquariadise
2. Assassin Snail (Clea helena) Care | The Snail-Eating Snail - The Shrimp Farm
3. Buy Assassin Snail - Clea helena at The Shrimp Farm
4. Effect of Diet and Stocking Densities on Life History Traits of Clea helena (Philippi 1847) Reared in Captivity