Planarien in the Aquarium

If you maintain an underwater world with dwarf shrimp and snails, planarians are one of the biggest threats to your pets. Despite their small body size, predatory flatworms are often considered ruthless predators of dwarf shrimp, etc. However, not all worms that enter your aquarium belong to these dreaded planarians. A closer look can often provide an early indication of whether your underwater landscape is in serious danger or not.

In our article we will show you which characteristics you can use to identify planarians more or less well, what exactly these feared intruders are and what you should do if this predatory species spreads in your aquarium.

What are planarians?

The word planaria comes from Latin airplane from that as much as Dish means – this is why planarians are sometimes called flatworms because they are flattened, worm-like animals. They move using the skin and muscles inside the body. Planarians can be native to both land and water; planarians living in freshwater usually only reach a maximum body length of 2 cm, although of course there are exceptions – such as: B. the giant forms found in Lake Baikal, which are said to be up to half a meter long.

Planarians are considered a predatory species, but in the wild they also feed on carrion – when it comes to choosing prey in your aquarium, planarians are usually efficient and rather slow: although they can be dangerous for shrimp, especially after moulting, they prefer easier prey such as snails, dead, very young or weak animals and fish eggs.

How do you recognize “true” planarians?

In order to distinguish a planarian that is more dangerous to your underwater world from a worm that is harmless, it is useful to be able to identify a planarian as clearly as possible.

There are some very clear physical characteristics that distinguish the dreaded flatworm, which we have summarized for you here:

If you recognize some or all of these characteristics in the worm-like intruders of your underwater world, there is a high probability that they are indeed planarians.

How do planarians get into the aquarium?

Planarians are hardy and capable of survival – in particular, their egg cocoons, which are laid as permanent eggs, are nearly indestructible as they are insensitive to many chemicals, dryness and heat. Planarians can also reproduce asexually through division. Planarians often enter your aquarium as stowaways. Their eggs attach themselves to plants, stones or other decorative objects or come into direct contact with other aquarium inhabitants, for example. B. likes to hide in the mantle cavity of snails.

What to do with planarians in the aquarium?

If you are sure you have spotted planarians in your aquarium, the first thing to do is stay calm: although the dreaded flatworms represent a threat to your underwater world that should not be underestimated, some simple and effective measures can lead to a permanent reduction in the planarian population in your aquarium.

It cannot be denied that, in addition to snails, dead, sick, weak or freshly skinned shrimp are also easy prey for planarians: they also appreciate young fish or fish eggs as a delicacy.

Planarians can also be dangerous to dwarf shrimp, especially after moulting.

If planarians find enough food, they begin to reproduce rapidly, either by division or by laying extremely robust egg cocoons. However, it is important to remember that flatworms do not always have to be the cause of shrimp death in the underwater world. It may also happen that, for example, if bacterial infections or poor water hygiene have already weakened the immune system of your shrimp, the mortality rate increases, so that planarians that may already be in the tank come into play: they benefit from the sudden excess of food and begin to multiply rapidly. This means that prevention plays an important role in the fight against planarians, because healthy shrimp with a stable immune system are only half as attractive prey for hungry planarians as dead or weakened animals.

Planarian traps

One way to significantly reduce the planarian population in your aquarium is to use so-called planarian traps. These exploit the culinary preferences of small parasites, whose preferred food source is meat.

You can equip planarian traps with fresh meat, which emits a scent that is irresistible to planarians. If they follow their instinct and crawl into the trap, there is no escape, because due to its structure the worms can enter the trap but cannot get out. Once the trap is full, you can take it out of the tub and rinse it with warm water. Of course, you will have to repeat this procedure several times because you have to assume that there will be a large number of planaria eggs in your aquarium. When repeating, the period of two weeks should not be exceeded, as newly hatched planarians need fourteen days to become sexually mature and then quickly begin breeding again.

Important: To kill planaria, always rinse the traps well with boiling water and do not simply empty them down the drain. Planars are survival artists; if they end up alive in the sewers, in the worst case scenario they can even endanger the local fauna.

When used consistently, planarian traps offer a useful method to permanently keep the planarian population in your aquarium under control and massively reduce it. In many cases, this approach, combined with careful care, is sufficient to adequately protect the underwater world.

Planarian traps can make a significant contribution to reducing the planarian population in your aquarium.

After all, collecting worms only makes sense to a very modest extent, since planarians hide well and therefore only a fraction of the predators will attract your attention.

Drug

Sometimes special preparations based on worms are recommended as a way to combat planaria. However, these were originally developed to treat worms in dogs and cats and are not approved for use in aquariums. It is important to note that these drugs are fatal to most snails and invertebrates, and there are no valid studies on the exact dosage. These products are therefore not suitable for an aquarium in which snails and invertebrates live! The use of these prescription preparations should only be carried out in close collaboration with a veterinarian experienced in the field of aquarium keeping.

Predators

Basically planarians are not very tasty, so they hardly have predators that can effectively support you in the fight against small parasites. However, there are some aquarium inhabitants who do not despise bitter worms, although they often only resort to worms when no alternative food is available. Additionally, some of the fish that feed on planarians also tend to feast on shrimp rather than planarians, so they can often prove unsuitable or counterproductive for anti-planarian use in your aquarium. The dwarf tiger loach and red claw shrimp are said to have an appetite for bitter flatworms.

Unoccupied aquarium

In an aquarium without stock the possibilities for fighting planarians are wider: for example it is possible: B. by lowering the pH value an extremely acidic environment can be created in which the planarians dissolve. For this it is necessary to create a pH value below 4 – e.g. B. through the use of citric acid. Sensitive aquarium plants may be affected by the procedure, but most plants survive this procedure relatively well. However, the planarian eggs remain intact, so it is necessary to repeat the treatment after two weeks when the chicks have hatched but have not yet reached sexual maturity.

A high concentration of CO2 also kills planarians and is another way to combat unpleasant parasites in the aquarium. But even in this case the procedure must be repeated after two weeks.

Prevention measures

Although planarians usually enter your underwater world as stowaways, a few tips can help reduce the risk of a planarian infestation.

So it can e.g. For example, it may be helpful to use in vitro plants when planting your aquarium or, in general, send your aquatic plants into quarantine for at least two weeks to ensure you haven’t overlooked any planarian eggs. Decorative items should also be carefully examined for the presence of small egg cocoons and, if possible, rinsed with boiling water to ensure that no stowaways enter your aquarium with them. Planaria eggs are also said to have entered the aquarium through frozen food, so a closer look may be helpful to prevent planarians from spreading into your aquarium.

Conclusion

Planarians always represent a certain danger for your underwater world: especially sick, very young or weak animals, as well as snails and fish eggs, represent easy and therefore appreciated prey for them. With an ample food supply, they multiply rapidly. However, it is important to remain calm if the situation worsens. First you should be sure that the worm-like animals in your aquarium are really planarians and not other, perhaps completely harmless, worms. If you are sure that predatory planarians are spreading in your tank, it is important to deprive them of their food source as much as possible, ensuring the well-being of the aquarium inhabitants and healthy water hygiene as best as possible.

Planarians often pose less of a threat to healthy aquarium inhabitants.

Planarian traps usually offer an effective and sufficient way to decimate the planarian population in your aquarium so that there is no longer any danger to your underwater world. In an aquarium without livestock, you have other methods available to get rid of unwanted worms. In any case, keep in mind that the respective measurements should be repeated several times at intervals of approximately two weeks in order to be able to remove the newly hatched planarians from your aquarium before they reach sexual maturity. Also ensure that planarians do not end up alive in the sewer system, as this could cause harm to local wildlife.