Assassin Snail Helena – what You need to know

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Anentome (Clea) helena, also known as bloody helena or an assassin snail, is a species of snail desirable in aquariums due to its unusual diet. It is a small predator that actively hunts other snails. Therefore, it is used for the ecological fight against the plagues of Ram’s horn snails (Planorbarius corneus) and Bladder snails (Physidae). Especially in shrimp tanks.

Origin of Assasin Snail Helena

Helena naturally occur in Southeast Asia (Thailand, Cambodia, Malaysia, Indonesia). They can be found in shallow, clear waters with a sandy bottom.

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Anetome (Clea) Helena grow up to about 2 cm. Their conical shells are fitted with a lid. They are decorated with alternating yellow and brown stripes. There are also examples with one-color shells. The leg of the snail is gray, as if marbled. They have two trumpets: one is used to locate prey and is easy to spot when the snail wanders around the aquarium. The second trumpet is longer, used to suck victims from their shells.

Assasin Snails Helena are more active at night, but they also hunt when hungry during the day. They move relatively quickly. When not hunting, they bury themselves in the ground. They do not like climbing plants, they mostly wander along the bottom and shafts of the aquarium.

Requirements for Helenas

Like every snail, it needs water with an appropriate calcium content, i.e. medium hard or hard, pH approx. 6.0 – 8.0. In soft water, their shells will dissolve, which will be visible in the form of unattractive holes. They prefer sandy or fine gravel. They are suitable for almost every aquarium over 25 l. The optimal density is 1 snail per 10 l. They prefer temperatures in the range of 22-28 ° C.

Anetome (Clea) Helena nutrition

As I have already mentioned, Helenas are a ravenous rarity among snails. They wander around the aquarium or buried in the ground waiting for a victim. They eagerly feed on other snails like Ram’s horn or Bladder snails. However, when hungry, they can hunt much larger snails, even Apple snails (Ampullariidae). Military Helmet and Neretina snails are theoretically safe due to their strong lids.

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They do not disdain carrion, but they do not touch healthy shrimps – they are too fast for them. Some aquarists, however, insist the opposite opinion, but these are really rare situations. Either way, helenas are the most effective way to exterminate the plagues of other snails in shrimp tanks. We cannot use slugicides in them, because they are based on copper compounds, which is also lethal for shrimps. On the other hand, snail-eating fish are eliminated due to the small volume of such aquariums and the fact that they also do not despise shrimp.

If they have nothing to hunt, they eat almost any fish or shrimp food. It is worth ensuring that it is high in protein.


I have not found any reliable information about the sexuality of Helenas. Some claim that they are dioecious, but it is impossible to distinguish between the sexes. Others opt for androgynism and cross-fertilization. Personally, I am inclined to the latter opinion. I am convinced that if we only have one snail of this species, after some time we can wait for the young. The chances of buying a “female” pale in comparison to the fact that zwitterionic snails have the ability to store sperm obtained from other animals during cross-fertilization.

Helenas eggs are in the form of “fried square eggs”. They are scattered individually on the lower parts of plants, on stones or wood. They develop about 3-5 weeks at 25-26 ° C, although this time depends on the temperature. Only after some time do young specimens begin to take shape and color like adults.

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Animal at home is a project derived from the Polish portal dedicated to domestic pets, which I run. This blog category features the best articles I have created with pet experts. Together, we help educate their current and future owners.

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Jakub Markiewicz
Jakub Markiewicz
Hi, I am the author of the blog and series of thematic portals since 2013. I have nearly 15 years of experience in working in the media, marketing, public relations and IT. If you are interested in cooperation, you would like me to write about something or test a product - let me know.