Assassin Snail

The Assassin Snail (Clea helena) is a highly effective, natural solution for controlling pest snail populations in freshwater aquariums. Known for their striking yellow-and-dark-brown banded shells and purposeful movement, Assassin Snails are both attractive and functional. Unlike many snail species, they are carnivorous and help manage populations of bladder, ramshorn, pond, and Malaysian trumpet snails without harming fish or plants. Peaceful, hardy, and easy to care for, they make an excellent addition to community tanks of all sizes.

Care Sheet – Assassin Snail (Clea helena)

Temperament

• Peaceful toward fish and invertebrates

• Predatory only toward other snails

Adult Size

• Up to ~1 inch

Minimum Tank Size

• 5 gallons (larger recommended if they will be controlling a large pest snail population)

Water Parameters

• Temperature: 72–82°F

• pH: 7.0–8.0

• Hardness: Moderate to hard water preferred

• Ammonia/Nitrite: 0 ppm

• Nitrate: <20 ppm

Diet

• Carnivorous

• Feeds on pest snails

• Can also be fed supplemental protein such as:

  • Sinking carnivore pellets

  • Frozen bloodworms

  • Snail jello or crushed snails (if natural food supply is low)

Behavior & Compatibility

• Safe for fish and shrimp

• Will not eat healthy plants

• May prey on small decorative snails (Nerites usually safe; Mystery snails not recommended as tankmates)

Breeding

• Lay single eggs on hard surfaces

• Slow, steady breeders—not invasive

• Require male and female pairs (not hermaphroditic)

Special Notes

• Excellent biological pest control

• Hardy and adaptable

• Avoid copper-based medications

• Will burrow in substrate, especially sand