Marine Invertebrates

Snail Helena

  • Scientific name:  Anentome Helena
  • Common name:  Helena Snail or Assassin Snail
  • Aquarium size:  20 liters and up
  • Temperament: Calm
  • Temperature:  Between 22 ° C and 26 ° C
  • pH: Between 6 and 8
  • Diet:  Carnivore
  • Length:  2 cms to 2.5 cms


The Anentome Helena is also known as Helena Snail or Assassin Snail due to its preference for feeding on other snails.

This aquatic mollusk is native to Southeast Asia, and
is a species commonly used in aquariums because it is a carnivorous snail that helps fight pests from other snails.

As a curious fact,
in Vietnam it is highly valued as part of the traditional cuisine of that country.


Commonly called the Assassin Snail, it has a spiral-shaped striated shell with yellow and brown or black stripes. In addition, these snails have two horns, and a trunk similar to a transparent hollow tube, which they use to locate their prey using it to feel and perceive the movements of the water waves.
It can live for about 5 years, and in optimal conditions about 9 or 10 years, reaching a maximum size of about 2.5 to 3.5 centimeters.

Distribution and habitat

The Killer Snail likes to live in rivers and swamps with sandy bottoms so that it can bury itself . They are frequently found in calm waters.
It comes from Southeast Asia, specifically the Island of Java, Vietnam, Indonesia, China and Thailand.

Aquarium Conditions

The Helena Snail does not require large spaces or conditions that are too specific for its maintenance, nor is it necessary to have special lighting or vegetation, as it adapts well to the normal general characteristics of any aquarium.

However, the important thing is to
maintain very clean habitat conditions and as close as possible to their natural environment. For this reason, it is necessary to regularly change the water in the aquarium.

  • These snails need a pH 7
  • A gH 8-18
  • The water temperature should be about 24 degrees centigrade approximately

In short, the Anentome Helena or Assassin Snail is an ideal specimen for our aquarium, since it can help us with the pest control of other snails and at the same time collaborate with the elimination of carrion remains, food remains, dead leaves, etc. . In addition, it is also a beautiful animal that can very well beautify and enrich our aquarium.


Assassin snails are carnivores and feed mainly on other snails such as Phisas, Planorbis or Melanoides.

Although their diet is based on other types of snails, it should also be noted that in their natural habitat or in the aquarium, they
can also consume carrion and other debris such as dead plant remains. On the other hand, they can also eat scraps that fall to the bottom of fish food.

the Helena Snail does not eat its own species,although it has been evidenced in some not very frequent cases, the presence of empty shells of the Assassin Snail at the bottom of the aquariums, thus evidencing cannibalism within the same species. For this reason, this snail very well lives up to its reputation as a murderer.

Behavior and compatibility

In general, it is a very peaceful animal. It gets along well with other species of animals except for fish that eat snails (such as the Botia Clown or the Puffer Fish ).

Also, inside the aquarium they
can be kept together with prawns ( shrimp ) , although in some cases attacks on them have been documented, but they are usually specimens that were sick or weak for some reason.

On the contrary,
with other snails it is quite aggressive.

The Assassin Snail will attack and hunt any snail that is near it, unless its size is really intimidating to them.

On some occasions they can be seen taking small walks and moving calmly around the edges of the urns or fish tanks and then return to the water.


The Helena Snail, unlike many species of snails, is not hermaphrodite, that is, for its reproduction the presence of a male and a female is necessary.

The physical or morphological differences between the male and the female are negligible, that is, they are not distinguishable at first glance.
For this reason,
the aquarium must have several specimens (between 7 and 8 approximately) to ensure the existence of both sexes and thus their reproduction is possible.

Fertilization occurs with a «hug» between the male and the female that can last several hours.

Once the female is fertilized, it proceeds to lay between 10 and 20 small eggs overnight.1 to 1.5 mm square in shape surrounded by a gelatinous mass.

Unlike other snails that lay their eggs in clusters, the Helena Snail lays them one at a time across the entire surface of the aquarium.
Normally, not all the eggs will hatch.

After fertilization, the Helena Snail lays its eggs on logs or stones in the water , the shape of the eggs is similar to that of a small square and transparent sac.

After a couple of weeks, the eggs hatch and a 0.5 mm snail emerges, which buries itself and remains thus feeding on small microorganisms, carrion and other debris until it is fully formed with a size of 5 mm.
At that time it will be possible to see it looking for small snails to feed themselves.

Photos and images of Helena Snail

Video of the snail Helena, the killer snail

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