How to Get Rid of Hydra in Your Aquarium
You may have seen a tiny tentacle monster in your freshwater tank. Not to worry – it’s a fascinating freshwater creature called hydra that is relatively easy to deal with. Continue reading for more information about hydra. We also discuss natural ways to remove them from animals, plants and beneficial bacteria.
What is Hydra?
These tiny, freshwater organisms of the genus Hydra are the distant relatives of jellyfish, corals, and sea anemones. They can grow up to 0.4 inches (1 m) in length and range in color from translucent to light brown to green to dark brown. Hydra is similar to a sea anemone. It has a stalk or foot which attaches onto surfaces like glass, hardscape or plants. The mouth is at the end and is surrounded with long, wispy tentacles. These tentacles contain stinging cells, which are used to paralyze prey and catch them.
Because of their immortal cells and strong regenerative abilities, scientists have been fascinated by hydra for a long time. If a hydra is split into pieces, each fragment regenerates to become a new, individual hydra. They can also reproduce sexually through the production of buds and eggs.
The green pigment of green hydra (Hydraviridissima), is due to a unique and symbiotic relationship between photosynthetic Chlorella alga.
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. If you have wild plants or live foods, hydra can be brought in.
Is hydra harmful to humans? The stinging cells of hydra are too weak to cause any harm to humans. If you try to touch them, they quickly retract their tentacles and ball up to avoid predation from larger animals.
Are Hydra bad for aquariums. Hydra are ambush-hunters that like to eat microworms larvae and small crustaceans (e.g., baby brine shrimp, daphnia 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
Manual removal is not recommended unless you are able to hold a steady hand with a small number of hydra. You can accidentally cut off any hydra pieces and they will grow back into new hydra. Instead, we first recommend that you
Reduce food consumption
Going into the tank. When hydra don’t get enough food, the majority of them will starve to death 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 particularly prominent in fry grow-out tanks and shrimp-only aquariums because we purposely overfeed them with hydra-sized foods like baby brine shrimp or powdered fry food. Additionally, any potential predators larger than a hydra can be removed. 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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