Do Assassin Snails Kill and Eat Mystery Snails?

The assassin snail (Anentome helena), also known as the bumblebee snail, gets its name from its reputation for killing and feeding on other snails. Its slow movement makes most beginner aquarists think the snail won’t hunt down and kill other aquarium snails, such as mystery snails.

But can you keep assassin snails and mystery snails in the same aquarium? What will happen?

Will assassin snails kill mystery snails?

When kept together, assassin snails will kill and eat mystery snails. They prefer to eat smaller snails over larger ones, so they will target baby mystery snails first. If there aren’t other food sources, hungry assassin snails can gang up to attack and kill adult mystery snails and feed on them.

In large aquariums with freely-reproducing mystery snails and fish as tank mates, assassin snails can be introduced carefully to help control snail populations.

Are assassin snails aggressive?

Assassin snails are considered peaceful and non-aggressive, despite being well-known for their predatory behavior.

They’ll be peaceful towards most tank mates in the aquarium and tend only to attack and eat other snails, especially when hungry or when there aren’t enough food sources available to them.

While they’re considered slow-moving snails, they are quite fast at eating other pet snails and can deplete the population of their prey in an aquarium within a very short period.

Boris W. Berkhout and Andrew Morozov, in their research paper published in the Plus One Journal, term assassin snails as specialist predators with a unique model of attack compared to generalist predators.^[1]

Feeding habits: What do assassin snails eat?

Assassin snails are carnivorous, and their diet comprises worms (gastropods) and other species of snails. They’re also opportunistic feeders and will scavenge on decomposing fish and other small invertebrates in the aquarium.

These snails are very active at night as it is the best time to capture their prey unaware. When they hunt during the day, assassin snails bury themselves underneath the substrate at the bottom of the tank and wait for prey to approach.

Their first choice will be to feed on trumpet, rabbit, ivory, and Ramshorn snails. However, in the absence of live prey in the tank, they will feed protein-based foods, including the following:

Ensure to feed assassin snails sinking food because they love feeding at the bottom of the tank.

Snail population controllers

Snails like mystery snails reproduce really fast and can overpopulate the tank if not controlled. A common practice among aquarists is to introduce one or two assassin snails to control the population of mystery snails and other pet snails.

Take note: If you introduce assassin snails in a tank with few snails to control the population, they’re likely to kill all the mystery snails within a short period. A single assassin snail can eat about one small snail daily and a bigger snail for less than two days.

However, I find them the best predators for getting rid of those tiny snails that infest aquariums.

Considering their vast appetite, you need to figure out how many snails you want to get rid of in your aquarium before introducing assassin snails in the tank.

How to keep assassin snails with mystery snails safely

Assassin snails are normally kept to control the mystery snail population in the tank since they reproduce and multiply fast.

If, after considering the risk, you still want to keep the two types of snails together, here are tips to keep them together safely:

1. Provide adequate food for assassin snails

Adult mystery snails are usually bigger than assassin snails. Since assassin snails prefer to feed on smaller snails, they might not consider the mystery snails their first food choice.

Bumblebee snails will only attack mystery snails when starving. Therefore providing enough food in the tank will lower the chances of the assassin snail killing mystery snails.

We recommend providing enough protein-based food like blood worms, brine shrimp, and fish pellets.

2. Put other types of small snails in the tank

Assassin snails love to feed on smaller snails, and when added to the tank, the assassin snail will not eat mystery snails.

However, if you must have the killer snail in your tank, ensure you have a big tank that comfortably fits all the snails.

3. Keeping fewer assassin snails

Assassin snails are known to team up and attack a bigger snail. So to ensure this does not happen, keep only a few assassin snails.

You can keep one assassin snail in a tank for every five adult mystery snails. The ratio will ensure the assassin snail will keep the population in check but won’t finish all the mystery snails.

4. Keep baby mystery snails in a separate tank

Assassin snails prefer to feed on smaller snails, and baby mystery snails will always be a target. If you plan to increase your mystery snail stock, I advise that you hatch the eggs and rear the hatchlings in a separate tank.

You should add them back to the parent tank when they are bigger than assassin snails.

However, if you do not intend to increase the number of mystery snails in your tank, you can keep the hatchlings in the tank, and the assassin snail will feed on them.

References

• Berkhout, B. W., & Morozov, A. (2022). Assassin snails (Anentome helena) as a biological model for exploring the effects of individual specialisation within generalist predators. PLOS ONE, 17(3), e0264996. https://doi.org/10.1371/journal.pone.0264996