Assassin Snail (Clea helena or Anentome helena)

The Assassin Snail (Clea helena or Anentome helena) is a popular freshwater snail native to Southeast Asia, prized by aquarium hobbyists as a natural biological control for pest snails. They are slow-moving but efficient carnivores that hunt, kill, and eat other snails.

🐌 Appearance & Behavior.

Bumblebee Shell: They feature a distinctive, cone-shaped spiral shell with alternating dark brown and yellow-tan stripes.

The Siphon: You will often see them crawling around with a long, snorkel-like tube (siphon) extended. They use this tool to breathe while buried and to "smell" out their prey.

Ambush Predators: They are nocturnal and spend much of their day buried underneath sand or fine substrate. They wait for a pest snail to pass by, then strike from below.

Size: They reach a maximum adult size of about 1 to 1.25 inches (2.5 to 3 cm).

Diet & Hunting

Primary Target: They eat small pest snails like bladder snails, ramshorn snails, and Malaysian trumpet snails.

The Kill: They overpower prey using a muscular foot, then insert a trunk-like proboscis into the victim's shell to digest it.

Alternative Diet: If they run out of pest snails, they will not starve. They switch to scavenging on leftover fish flakes, shrimp pellets, wafers, or dead tank mates. They do not eat live aquarium plants.

Compatibility & Tank Mates

Safe Choices: Community fish (tetras, guppies, bettas) and peaceful bottom dwellers.

Risky Choices: They generally leave larger ornamental snails (like large Mystery or Nerite snails) alone because they cannot easily overpower them. However, a large pack of hungry assassin snails may gang up on a large snail.

Shrimp: Use caution with dwarf shrimp. While shrimp are usually too fast to be caught, an assassin snail might catch a molting, sick, or sleeping shrimp.