Assassin Snail

Anentome helena

Also sold as Anentome

Synonyms Clea helena · Assasin snail · Bumblebee snail

Assassin Snail (Anentome helena) is a semi-aggressive freshwater snail that reaches about 3 cm (1.2 in) and swims along the bottom. It wants 72–82°F (22–28°C) and pH 7–8, can be kept singly, and needs a tank of at least 10 L (3 gal).

At a glance

Type	Snail
Adult size	3 cm (1.2 in)
Minimum tank	10 L (3 gal)
Group size	Can be kept singly
Temperature	72–82°F (22–28°C)
pH	7–8
Temperament	Semi-aggressive
GH	6–20
Lifespan	2–3 years
Eats shrimp	Shrimplets only

Before it goes in

Assassin Snail needs at least 10 L (3 gal). The smallest size in this library that clears that is the 45F Shallow.
Adult shrimp are safe; shrimplets will be eaten, so a shrimp colony will not grow in the same tank.
It holds at 72–82°F (22–28°C). That shares a window with Betta and Cherry Shrimp.
Do not put it with Bladder Snail, Malaysian Trumpet Snail and Ramshorn Snail.
It can go wrong with Mystery Snail and Nerite Snail — it works in some tanks and not in others, so it is not a combination to buy blind.
It is semi-aggressive — plan the tank around it rather than adding it to a finished community.

What tank size does it need?

At least 10 L (3 gal). The smallest size here that clears it is the 45F Shallow.

Will it eat shrimp?

Adults are safe, shrimplets are not. You can keep shrimp with it; you just will not get a growing colony.

What water does it want?

72–82°F (22–28°C), pH 7–8, GH 6–20.

How long does it live?

2–3 years in a tank that suits it. That is how long you are signing up for.

Good tank mates

Tank mates from this library that share its temperature window, are peaceful and eat neither it nor its young: Cherry Shrimp, Goldfish, Bristlenose Pleco, Celestial Pearl Danio and Molly.
Plants that hold up with it: Hygrophila corymbosa 'Siamensis', Water Sprite, Anubias nana 'Petite' and Cryptocoryne wendtii.

Often compared with

	Assassin Snail	Malaysian Trumpet Snail	Nerite Snail
Adult size	3 cm	3 cm	2.5 cm
Min tank	10 L	5 L	10 L
Group	1+	1+	1+
Temperature	72–82°F (22–28°C)	68–86°F (20–30°C)	68–82°F (20–28°C)
Eats shrimp	Shrimplets only	No	No

More livestock

Plan a tank with Assassin Snail →

Sources (5) · checked Sep 2026