Hydras as a problem in aquariums

Hydras are carnivorous and have stinging cells. They will compete with fish for live food. Although they are too small to eat adult fish, I wonder if they stress smaller fish like the Neon Tetra by stinging when they accidentally touch the hydras.

Another problem is simply that some people don’t like the way they look.

However, the biggest problem arises with infestations in breeding tanks when people try to raise egg-laying fish. Hydras eat the live food that is put into the tank for the baby fish; multiply quickly and eat the little fish.

There are several suggested ways to get rid of Hydra infestations. Most of these ways would certainly kill baby fish, and there are none that I would consider safe with them. So if you expect hydras to be a problem, you should get rid of them from your breeding tank before they breed.

Ways to remove Hydra

Fish

In a normal aquarium, what I like best is to use fish that eat them. The most common used is the Blue Gourami.

Heat

A temperature of 41 degrees C (106 degrees F) for three days will apparently kill the hydra. It will also kill almost all types of fish, so these will need to be removed. Some plants will survive this heat treatment.

chemicals

Naturally, things like chlorine bleach will kill hydra just as well as most other things. This can be used to sterilize non-living things like rocks, and has even been used successfully to destroy entire aquarium pests and diseases. Of course it will kill any plants and fish. Considerable effort is needed to ensure that no residue remains before living things are reintroduced.

In addition to these drastic chemicals, there are several that can be used on fish, but not absolutely safely.

Copper it can be used, but maintaining the correct level is difficult in a freshwater aquarium. Additionally, some studies suggest that many fish are more susceptible to copper than Hydra.

Formaldehyde at 3 drops per US gallon it seems to kill most hydras without killing the fish. However, you may not kill them all with a single dose. Note that formaldehyde will lower the pH of the water as it breaks down into formic acid. The pH would have to be monitored and adjusted as necessary.

flubendazole It is an anthelmintic drug. It will get rid of some internal fish parasites, as well as Hydra, ick (white spot), velvet and gill flukes. It is possibly the safest of the chemicals that will kill Hydra. A guideline for the dose needed is 1/2 gram of flubendazole 10% per 20 liters (5 US gallons).

With any chemical, remember that different types of fish are likely to have different tolerances, and different species of Hydra can also vary considerably in their susceptibilities to the chemical.

It’s also worth considering whether you really need to get rid of the hydra in your aquarium. regular maintenance; not allowing your aquarium to get dirty will help prevent a large buildup of Hydra.