Assassin snail

Overview

Assassin snails (Clea helena) are the hobby’s natural pest-snail control — attractive yellow-and-brown striped carnivores that hunt and eat bladder, ramshorn and small trumpet snails. They burrow in the substrate, ambush prey and steadily clear an infestation over weeks. Peaceful toward fish and healthy shrimp, they’re a genuinely useful, good-looking addition rather than just a tool. Their conical striped shells are attractive in their own right, and once the pest snails are gone many keepers happily keep a small group on as a permanent, low-key part of the community.

Tank & water

A 38 litre (10 gallon) tank gives them room to hunt over a soft, burrowable substrate:

• Sand or fine gravel — a soft substrate lets them bury and ambush prey.
• A cycled tank — cycle fully; they still dislike ammonia and nitrite.
• Harder, alkaline water — pH above 7 with some hardness keeps their shells solid.
• No copper — lethal to snails and shrimp; check medication and fertiliser labels.

Feeding

Assassin snails are carnivores. While pest snails last they largely feed themselves; once prey runs low, offer meaty sinking foods — frozen bloodworms, protein-rich sinking pellets or carrion. They won’t graze algae like other snails, so a well-fed assassin colony still needs an occasional protein feed to stay healthy. Bear in mind that clearing pests can take several weeks, and once the food supply crashes their own numbers ease off, so plan to supplement rather than expecting them to thrive on pests alone forever.

Tankmates & breeding

Assassin snails are peaceful toward fish and healthy shrimp but predatory toward other snails, so don’t mix them with nerites or mystery snails you want to keep. They breed slowly, laying single eggs, so numbers stay manageable — unlike the pests they control. A small group is easy to keep in balance.

Manage a snail boom by pairing them with fewer feedings; compare ramshorn, bladder and Malaysian trumpet snails.