Creating the Perfect Habitat for Assassin Snails

Assassin snail (lat. Anentome helena (formerly Clea helena)) comes from South-West Asia, it’s often called an killer snail. Assassin snails are small freshwater snails that are highly sought after for their ability to control unwanted pest snail populations in aquariums. So, if your tank has been occupied by snails, Anentome helena – is one of the most popular and efficient ways to get rid of tank snails.

Do assassin snails eat other snails?


Some snails due to their fast breeding can become a real disaster in a tank. Some species can get into the tank accidentally together with plants (such as great ramshorn), Physa fontinalis, Acroloxus family species, and some of them – like malaysian trumpet snails, were bought to dig the bottom substrate.

Sometimes it’s possible to take them out, but it just partially solves the problem and gives a temporally result, since to clean from these species completely all the substrate and the plants in a tank is impossible.


  1. assassin snail eat overpopulated species of ramshorns and MTS in a tank
  2. they don’t dig the tank bottom substrate, though they can deepen into it a little
  3. their diet doesn’t include live fishes and prawns
  4. assassin snails don’t feed on tank plants
  5. their breeding doesn’t require any special tank conditions

Habitat in the wild

In the wild assassin snail inhabit in not very deep waters with pure water on the South-West of Asia – in Thailand, Malaysia, Singapore, and Indonesia. They inhabit rivers, streams, and other freshwater bodies in these regions. Assassin snails are typically found in slow-moving or stagnant waters, including marshes, ponds, and ditches. They prefer areas with dense vegetation and substrate rich in organic matter.

Assassin snails are bottom-dwelling species and prefer sandy or muddy substrates. They burrow into the substrate using their foot to find shelter and search for food. Assassin snails are predators and scavengers which feed both on live snails and on carrion or decaying organics, and this is what made them popular tank inhabitants. They are opportunistic predators, hunting and consuming other snails to meet their dietary needs.


How big do assassin snails get? Adult Helena snails typically reach a size of about 0.5 in length, although there can be some size variation among individuals.

The Helena snail has a conical-shaped shell with a pointed apex. The shell coloration ranges from light to dark brown or yellowish-brown. It features distinct dark brown spiral bands or stripes that encircle the shell. Helena snails possess an operculum, which is a hard plate-like structure that covers the shell opening when the snail retreats inside. The operculum provides protection to the snail and helps maintain moisture within the shell.

It has gray body with dark spots on it. The snail’s body is soft and elongated, covered by a thin layer of skin. It has a retractable foot used for movement and burrowing into the substrate. They have a siphon-like structure called the proboscis or siphon, which extends from the front of the snail’s body. Elongated breathing tube is always stretched forward as the snail moves. The proboscis is used for sensory purposes, such as detecting food and environmental cues.

How do assassin snails kill? Once an assassin snail detects its prey, it will begin to pursue it. Assassin snails are relatively fast and agile, allowing them to catch up with and capture their prey. They use their muscular foot to move and navigate. Assassin snails have a long, extendable proboscis, which is a specialized feeding tube. They use this proboscis to deliver a harpoon-like radula, a rasping tongue lined with rows of sharp teeth, into their prey. Once the assassin snail has successfully harpooned its prey, it injects a toxin that immobilizes and paralyzes the snail. This toxin is believed to contain enzymes that break down the snail’s soft tissues, allowing the assassin snail to consume the prey.

How long do assassin snails live? The lifespan of assassin snails can vary depending on various factors, including their environment, diet, and overall care. In optimal conditions, assassin snails have the potential to live for several years. On average, you can expect assassin snails to live between 2 to 3 years. However, it’s important to note that individual lifespans can vary, and some may live longer or shorter lives.

Providing a suitable aquarium environment, maintaining good water quality, offering a balanced diet, and avoiding stressors can contribute to the longevity of assassin snails. Additionally, genetics and individual health play a role in determining their lifespan.

By providing a proper habitat and meeting their specific care requirements, you can help ensure that assassin snails have the best chance of living a healthy and fulfilling life in your aquarium.

Scientific NameAnentome helena; Clea helena
Common NamesAssassin snail, helena snail
SizeUp to 0.5 inch (15-17 mm) in length
Shell ShapeCone-shaped
Shell ColorYellowish-brown with dark brown bands
Native HabitatFreshwater rivers, streams, and slow-moving waters in Southeast Asia
BehaviorActive predators, hunt and consume other snails
PreySmall snails, including pest snails like bladder snails
CompatibilityGenerally peaceful, but may prey on small shrimp or baby snails
Minimum Tank Size10 gallons (38 liters)
Substrate PreferenceSandy or fine gravel
Water ParameterspH: 6.5-7.5, Temperature: 72-82°F (22-28°C)
FeedingPrimarily feed on other snails; can be supplemented with sinking pellets or tablets
BreedingLive-bearers, females give birth to live snails
Geographic RangeSoutheast Asia

Care and keeping in a tank

Care is rather simple since the assassin snail is an enduring one. As the majority of other snails they won’t do in too soft water, since they need some mineral substances for their shell.

Assassin snails are aquatic snails and are not adapted to live out of water for extended periods. They are not capable of breathing air like some other snail species that possess a lung-like structure called a “pulmonate” adaptation.

Can assassin snails live out of water? While assassin snails may survive brief periods of time outside of water, such as during tank maintenance or transfer, it’s crucial to minimize their exposure to air and keep them moist. Prolonged exposure to air can lead to dehydration and can be harmful to their overall health and survival.

Tank size

Assassin snails are relatively small in size and don’t require a large tank. However, it’s important to provide them with sufficient space to thrive and exhibit their natural behaviors. A minimum tank size of 10 gallons (38 liters) is typically recommended for keeping assassin snails. This size allows them to move around comfortably and have ample room to hunt for prey and explore their environment.

Keep in mind that if you plan to keep a group of assassin snails or have them coexist with other tank inhabitants, such as fish or shrimp, you may need a larger tank to accommodate the additional bioload and ensure adequate swimming and hiding space for all the inhabitants.

Providing a well-sized tank not only promotes the overall well-being of the assassin snails but also helps maintain stable water parameters and reduces the risk of overcrowding-related stress and health issues.

Water parameters

These snails are freshwater inhabitants and they don’t need any brackish water, though they can stand it rather well. Although water parameters aren’t a crucial point, but it’s better to keep snail in the slightly acidic to neutral water conditions. The recommended pH range for them is typically between 6.5 and 7.5.

Assassin snails are adaptable to a range of water hardness levels. They can tolerate both soft and moderately hard water. Ideally, the water hardness should be in the range of 4 to 12 dGH (degrees of general hardness).

The optimal temperature range for assassin snails is between 72°F and 82°F (22°C to 28°C). I


Due to such a peculiarity of these snails an ideal tank substrate for them is sand or small pebbles (after sifting) sized 0.5-1.5 mm. Juveniles feed like MTS species – they turn over the upper layer of the substrate looking for some feed leftovers. There’s no need in any specific feeding.

Assassin snail moves quite fast on any surface, which is especially noticeable when a hungry species was given some meal. After snail was fed it disappears as fast as it appeared – since it is a burrowing king of snails, it partially digs into the tank bottom substrate.


What do assassin snails eat? They are carnivorous and primarily feed on other snails. They are highly effective in controlling pest snail populations in aquariums.

Assassin snails actively hunt and consume other snails, including common pest snails such as bladder snails (Physella acuta), Malaysian trumpet snails (Melanoides tuberculata), and ramshorn snails (Planorbidae family). They are especially efficient at targeting and eliminating small snails. Hungry snail doesn’t care that the majority of its time MTS spends in a bottom substrate – the predators watch them when they are coming out on a surface and eat them. Buccal opening of assassin snails is a tube using which they suck out their victim from its shell.

However, snails don’t feed on apple snails (Ampularia spp.) eagerly, even the small ones they eat only in extreme cases. Apple snails and nerite snails are larger than the typical prey of assassin snails.

Food mainly consists of other snails, but if there are absent in a tank, diet can be complimented with other feed with high protein content. Frequently they may be fed with frozen blood worm and or sinking pelletsdesigned for carnivorous invertebrates. These foods should be rich in animal proteins to meet their nutritional needs.

Tank mates

Do assassin snails eat shrimp? They are predators only towards other small snails and they show no interest to fishes, shrimps and tank plants. Providing ample hiding spots, such as dense vegetation, rocks, or caves, can offer the shrimp places to retreat and seek refuge from the snails. This can help minimize the chances of direct contact between the snails and shrimp.

As we know, assassin snails don’t feed on adult apples snails and neritina snails – since their shell sticks very tight to the surface and Anentome helena can’t get the shellfish out of it.

Do assassin snails eat each other? While they are not typically cannibalistic, there have been reports of instances where assassin snails have been observed preying upon and consuming other assassin snails. Cannibalism among assassin snails is more likely to occur in situations where there is limited availability of their primary prey, such as bladder snails or Malaysian trumpet snails. When food sources are scarce, assassin snails may resort to cannibalism as a means of survival.

Assassin snail gender

Assassin snail are heterosexual, meaning they have distinct male and female individuals. But it’s almost impossible to define its gender by its appearance, so the only way to obtain their posterity is to keep several species in a aquarium. In general, female assassin snails tend to be slightly larger and more robust compared to males. However, this difference in size may not be very pronounced, and it can vary between individuals.


To initiate breeding, it’s essential to have a male and a female assassin snail. While it can be challenging to determine the gender of individual snails, maintaining a small group of snails increases the likelihood of having both males and females.

Assassin snails engage in a courtship ritual before mating. Couple getting ready for breeding is clearly seen in a tank – they move around the tank together one on another for weeks and they don’t get apart even when feeding. After successful mating, the female assassin snail will lay small, gelatinous egg capsules. These capsules usually contain a few dozen eggs and are attached to various surfaces in the aquarium.

What do assassin snail eggs look like? Eggs are small, gelatinous capsules that are typically translucent or light in color.

Both when keeping assassin snails and when breeding the parameters of tank water aren’t very important, however it was noticed that when the water temperature is below 20 C (68 F) the snails temporally stop laying the eggs.

For successful breeding it’s necessary to provide the breeding species with calm surroundings, give them enough feed and free them from intrusive tank mates, such as prawns and active fishes, especially cichlids, tiger вarb.

After coupling female lay eggs one at time on solid objects. They look like small boats with a yellowish bulb (0.1 mm in diameter) inside. Provided with optimal tank conditions one can get about 300 species less than is a year.

The eggs of assassin snails undergo an incubation period that usually lasts around 2-4 weeks, depending on the temperature and other environmental factors. Eggs hatching takes from 21 to 30 days and after that the juveniles hide away in the bottom substrate and live there till they are about 3-4 mm large.

Assassin snails have the potential to reproduce rapidly if conditions are favorable. Keep in mind that an uncontrolled increase in the assassin snail population may affect the overall balance of the aquarium. Regularly monitor and manage the population size to prevent overcrowding.