How To Get Rid Of Hydra In An Aquarium

Your aquarium is the perfect and natural home for your pet fish and shrimps.

But if you are not very careful, it can also be a haven for ferocious and destructive pests, diseases, invasive species, and aggressive algae.

One such pest is Hydra.  Not the many-headed serpent from Greek mythology, but instead the soft-bodied polyp that can be a blight for aquarium owners all over the world.

If you’ve started to notice Hydra popping up in your tank, it’s better to take action early, however, if you have an established infestation, all is not lost.

So, how can you get rid of Hydra in an aquarium?  The way to get rid of Hydra is by manually removing them whenever you see any, thoroughly cleaning any ornaments they are attached to.  However, if you want to look at some advanced techniques, read on. 

What Are Hydra?

These are tiny freshwater vertebrae and closely related to jellyfish and coral, which prey on small adult fish and shrimps. Although they appear quite small and undefined, they are fully grown animals, just like any other.

Basically, they are often described as having a tubular-like physique and measure just about a few milliliters. They possess one sticky foot on one side of the lower part their body, with almost a dozen tentacles forming the other parallel part of the body.

The tentacles are known to have stinging cells which are capable of attacking and immobilizing their prey. They also spit a highly poisonous substance, which can render their prey completely powerless and immobilized

In all the normal circumstances, they are accidentally introduced into an aquarium through a number of ways, and without visible evidence of their presence. Some appear to be brown, others are green or while others come with an off –white color. The best way and sure way to tell exact color is by use of a magnifying glass.

Hydra are both dangerous and destructive, as capable of killing and also feeding on Your shrimps, and any other small fish in your tank.

The worst thing and ever-present danger is that of their high and unrestrained regeneration capabilities. however negligent their numbers are, even a tiny pud, can fall off from the original and grow new hydra. If you think about it, they behave exactly like fungi, which has the capacity to regenerate and grow at any given opportunity, and under favorable environments.

Their nature of reproduction also means that however large the size of their prey is, they are still capable of feeding on it quite quickly. It is the reason these pests should never be welcome your aquarium in the first place; and in the event that they have already invaded, you should meticulously and quickly get rid of them.

How Do You Identify Hydra?

You just need to touch. These creatures respond more to touch than anything else.

They tend to wriggle, twist, and the turn into a ball, whenever they face any kind of threat. So generally, your touching them will stimulate the required response, and hence, confirming your worst fears that it’s indeed, hydra.

Hydra are typically just a few millimeters in length, so can be somewhat tricky to spot.

When you do see them, they’ll most often be greeny brown or a dirty white color, however, spotting the coloring with the naked eye is tough.

Most Hydra infestations I’ve come across have taken place in freshwater tanks, but there are varieties that will impact marine environments. Nobody is safe from Hydra.

Chances are if you’ve spotted one Hydra, there are more than a few lurking somewhere else in your tank.

Don’t be fooled by there appearance, these polyps can actually move around your tank and will multiply at an outstanding rate if given the opportunity to do so.

How Do Hydra Gain Entry into Your Aquarium?

These pests get cannot just into an aquarium out of nowhere. Evidently, they find themselves into the tank by hitchhiking on just about anything that could find them into the freshwater tank. Since they are highly invisible, they can hang onto the fresh plants which you submerge into the tank.

Again, their appearance can be quite deceiving to the eye. They basically look like a small piece of sand whenever the fold their tentacles and curl up. It means that they can also easily hang on to a fish bag and your tank just as easy.

Pre-treating your plants with hydrogen peroxide or a mild bleach solution can help an initial infestation.

Additionally, we always recommend netting new fish out the bag rather than pouring the content of the bag into your tank.  You don’t know what else can be included lurking in that bag water.

Even if you perform these precautionary methods, don’t be surprised if you still end up with Hydra.

How to Get Rid of Hydra In Aquarium

If you have confirmed that you are having a hydra infestation on your hands, it advisable that you take immediate steps to get rid of them. Sometimes it can be challenging, and you might encounter a few hurdles, but it’s not entirely impossible to rid your tank of the animals.

However, it also depends on the amount of infestation you have on your hands. If it’s minor and negligent, the process of elimination can be done manually. On the other hand, if the infiltration has escalated, then you may have to rely on other drastic removal measures such as chemical or heat.

1. Manual Elimination Method

You can physically remove hydra from the aquarium by several means.

• Since hydra is fond of attaching themselves on the inner surface of the glass, you can hold a soft cloth or wet sponge, and carefully wipe them off. Care must be taken, though, not to leave any lingering puds behind, as they will quickly regenerate and foster.

• You can also carefully remove the artificial plants and rocks from the tank, wash them thoroughly and air-dry them to make sure that the intruder is dead. While doing so, check that there are virtually no remnants in the tank.

2. Chemical Elimination Method

Most people prefer this method of removal as it’s quick and easy as well as effective. Another reason is that the chemical application can also eliminate all other pests such as planaria and scutariella, besides hydra.

Some of the chemicals on the market contain natural extracts, which basically target the hydra, and do not harm the fish in any way. Depending on the method of application, all pests in your tank do wither and die within a few days of the initial treatment.

But care must be taken, though. Not all chemical treatments are safe. They can be destructive to both plants and beneficial living things such as snails and the fish themselves residing in the aquarium. Again, these chemicals can greatly affect the good and beneficial bacteria in the tank.

It, therefore, means that chemical application should only be used as a last resort and more so, if the infestation has escalated beyond other friendly means of elimination.

Some of the commonly used hydra removal chemicals include Potassium Permanganate and Copper Sulfate. You can purchase them at any local fish shop in your area. Take in all the instructions so as not to cause any kind of harm to the fish or shrimps.

3. Hydra Predator Elimination Method

Adding hungry fish to the aquarium is one of the most friendly hydra elimination methods out there. In fact, it’s like killing two birds with one single stone; while the fish can feed and enjoy their meal, you also get rid of the hydra, leaving your smaller fish safe. Some of the fish that are usually used for this purpose include Blue Gourami and paradise fish. You can also use the mollies species.

However, if using fish is not your usual cup of tea, you can use pond snails, which are also capable of quickly destroying hydra and other deadly pests.

4. Heat Elimination Method

It is also another effective and cheap technique with which you can use to remove hydra. However, you must remove and relocate the fish and any other living as snails or they will be cooked in the heat.

The temperature of the water should be about 104 F / 40 C. It can be left to heat the tank for about 2 or slightly more hours to effectively kill the pests. You can then bring the heat down, do a light vacuum of the gravel and change about half of the water. Always ensure that the temperatures in the tank have actually dropped back to normal before you bring back the fish into the same tank

How Do You Prevent Hydra?

One of the best ways to completely keep hydra away from your aquarium, and your fish, is never to let them in, in the first place. In this case, prevention is the best solution.

As already mentioned, hydra do not just show up from o nowhere. Usually, and accidentally, they are introduced into the aquarium via an external source. However tiny and negligent hydras are, they begin to regenerate and multiply.

It is because of the favorable environment as well as sufficient food source which allow them to feed and grow. The following preventive measures can help.

– Always ensure that the tank is well-maintained and sparkling clean. Hydra has a way of getting into dirty tanks and quickly multiplying at a mind-boggling speed.

– Ensure that shops from which you buy your plants is reputed for their cleanliness.

– Carefully inspect any plants before submerging them into the tank.

– Soak the plants in quart water with an addition of alum into it. The process can take about 5-10 minutes; and then rinse the plants thoroughly with clean water, before you introduce them into the tank.

– The same process can be done once in a while for the rocks as well.

– Again, avoid situations of over-feeding your fish. Too much food increases the dirt, but also the likely infestation, of hydra. They can easily grow and thrive while feeding leftover food.

– Also make an effort to wipe off all leftover food, so that these creatures do not find any anything to feed on.


The truth is that hydra is intrusive and destructive pest which should never be allowed near your aquarium. Otherwise, the ultimate outcomes can be devastating, especially to your prized fish.

Preventive measures can be how to get rid of hydra in an aquarium and also keep the intruder out; but in the event that you have them already in the tank, you should make haste to remove them before they can grow in their large numbers.

The best thing is that you can also apply a number of options to completely get rid of the menace. From physically removing, them, to chemicals, heat, and predator elimination methods, you have the entire necessary arsenal at your disposal to remove all hydra from the aquarium.


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