How to Get Rid of Hydra in Your Aquarium
Have you spotted a miniature tentacle monster in your freshwater aquarium? You don’t have to worry about it – it’s a beautiful freshwater creature called hydra and is very easy to handle. Continue reading to learn more about hydra, and how you can remove them naturally without harming animals, plants, or beneficial bacteria.
What is Hydra?
These tiny, freshwater organisms of the genus Hydra are the distant relatives of jellyfish, corals, and sea anemones. Growing up to 0.4 inches (1 cm), they range in color from translucent white to green to light brown. Similar to a sea anemone’s hydra, it has a stalk, or foot, that attaches on surfaces (like glass, plants, hardscape, and glass), and a mouth at one end that is surrounded in long, wispy, tentacles. These tentacles have stinging cells that are used to paralyze and catch their prey.
Because of their immortal cells and strong regenerative abilities, scientists have been fascinated by hydra for a long time. Each fragment of a hydra can be regenerated to create a new individual hydra by being broken down. They can also reproduce sexually through the production of buds and eggs.
Hydra viridissima, also known as green hydra, has a unique relationship with photosynthetic Chlorella, which is responsible to its green pigment.
How did hydra get in my fish tank? In our experience, we’ve noticed that hydra often lays dormant in fish tanks for many months, but then the population blooms when you start heavily feeding baby brine shrimp. You can also suspect that the hydra may have gotten into your fish tank from decorations, rocks, driftwood, or aquatic plants that were infected. You can also introduce hydra if you get wild foods, plants, and hardscape.
Are Hydra dangerous for humans? No. The stinging cell’s power is too weak to harm humans. If you try to touch them, they quickly retract their tentacles and ball up to avoid predation from larger animals.
Are hydra harmful to aquariums? Hydroplanes are predators that eat microworms and larvae as well as tiny crustaceans like scuds and scuds. In our experience, they are a natural part of the aquarium ecosystem and do not seem to greatly impact baby fish and shrimp populations. Fry are too large to be eaten and have a strong flight response, which causes them to flee from any stimuli, such as a stinging tentacle.
How to get rid of Hydra
It is usually not recommended to manually remove hydra unless you have a steady hand or a small population. You can accidentally cut off any hydra pieces and they will grow back into new hydra. Instead, we first recommend that you
Reduce the food intake
going into the tank. If hydra aren’t fed enough, they will die from starvation and eventually disappear. Consider target feeding the fish or using feeding dishes for shrimp to prevent the food from spreading throughout the aquarium. Regular water changes and gravel vacuuming will reduce the number of fish to an almost unnoticeable level.
Another natural way to get rid of hydra is to put predators in their place. You can try just about any omnivorous or carnivorous fish that is small enough to notice the hydra – such as guppies, mollies, betta fish, paradise fish, and gouramis. If the fish do not seem to consume the hydra, try reducing feedings to whet their appetites.
Aquariums with adult fish and snails rarely get large hydra populations because hydra is a convenient source of live food.
Hydra are especially common in shrimp-only and fry-only aquariums. This is because they are fed hydra-sized food like baby brine shrimps or powdered fried food. Plus, we usually remove all would-be predators that are big enough to eat both fry and hydra. Luckily, you can add snails (like ramshorn, pond, and spixi snails) that are happy to consume hydra but are too slow to go after baby fish and shrimp. Snails are great at cleaning up food left over after frying.
People often prefer to use chemical treatments (such as deworming agents or planaria remedies) to kill hydra, but many of these methods are not safe for snails, shrimp, fish, plants, and/or beneficial bacteria. It is possible to treat live plants or decor before you add them to your aquarium. However, make sure to do your research to ensure that they are safe for aquatic animals and plants.
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