How To Combat Hydra Inside Shrimp And Fish Tank

Have you seen a weird, small, white creature with thin hairs on its head that look like a mini tentacle clinging to leaves or decorations inside your aquarium? They may be a hydra, a parasite that many fish tank owners have banned from their aquariums over time.

If you’re experiencing issues with Hydra, you have come to the right place. At this moment, we will discuss these unwanted pests from A to Z.

Dealing with them is relatively easy; even if you have no prior experience, you can still be successful. Keep reading this article to find out what they are, how to fight and prevent them, and other fascinating information about them.

What Is Hydra?

Hydra is a genus of tiny creatures that live in tropical water from the Cnidaria phylum and class Hydrozoa. Sometimes, these organisms are referred to as freshwater polyps. They are distant relatives of sea anemones, jellyfish, and corals, most of whom are marine inhabitants.

Antoni van Leeuwenhoek (1632–1723) is a person who first described the hydra in a letter that he sent to the Royal Society on Christmas Day, 1702. Biologists have long been interested in these organisms because of their ‘immortal’ cells and ability to regenerate from small parts.

Even if they are divided mechanically into several pieces, a hydra only needs about a week to restore its body into a functioning animal. Each fragment will regenerate and become a new individual; is it fascinating?

Hydra originates from temperate and tropical regions, and they can also be found in fish tanks as nuisance pests nowadays.

Hydras Appearance

Their appearance is unique and easily identifiable because it differs from that of other aquarium parasites. They have a tubular body with a sticky stalk or foot at one end that helps them attach their body to a surface (like decorations, plants, or wall glass).

While on the other end, there is a mouth encircled with 6-12 long and wispy tentacles. Same with their cousins, jellyfish, their tentacle parts have stinging cells to immobilize and catch their prey.

The Hydra genus consists of hundreds of species. Some are quite unusual, with their tentacles visible in white but their bodies invisible, translucent.

Mostly, the hydra is white, but a few species come with a green and brown tint. Some have long tentacles and stalks, while others are short on both.

Some have tentacles on their tentacles and can generate a truly bizarre organism. Some can reach more than half an inch in size, but other species only grow up to less than 0.2 inches.

Another species can build chains of polyps that reach more than one inch long. This species buds at the top ‘head’ of the organism, and they form a series of foot-on-head hydra, which can be 2 – 4 hydra long.

Other interesting facts are that the hydra does not have a brain, a respiratory system, a circulatory system, and even lacks any musculature. Nonetheless, they still cause severe damage to your pets, especially to the smallest populations.

Types Of Freshwater Hydra That Are Commonly Seen In The Shrimp Or Fish Tank

Even though there are many hydra species that are distributed across all regions, it’s too difficult to identify them specifically without microscopy. However, two species are exclusive, and they are the most commonly appearing in the planted tank:

Green Hydras (Hydra/Cholorohydra Viridissma)

This type has a bright green color, resulting from the presence of numerous algae on the hydra’s endodermal cells. These algae belong to the Chlorella (Zoochlorellae) genus and live as symbionts with the hydra.

Actually, hydra viridissma is usually present in a whitish color. Green algae perform photosynthesis and produce sugars on their bodies. Then it is used by the hydra as a return; the hydra, as a predator, provides nitrogen sources for the algae, which are getting from their diet.

Green hydra sizes are rarely more than 10 mm (0.4 inches) long. Their arms or tentacles are commonly about half their body length.

In nature, the green hydra generally inhabits slow-moving or still freshwater bodies in northern temperate areas. They are pure carnivores, typically eating tiny insects, crustaceans, cyclops, fish larvae, and annelids. They release mucus to stick to a surface using their basal disc.

Brown Hydras (Hydra Oligatics)

Hydra oligactis is distinct from other species. The brown hydra has longer tentacles that reach up to 5 cm (2 inches) or even more when relaxed.

Their column is pale, transparent, and brown, measuring approximately 15-25 mm (0.6–1 inch) in length. The base part of their column is narrowed to form a foot or stalk.

Hydra Body Structured

All species under the hydra family have a two-layered skin that is radially symmetrical and a tubular body that is split by mesoglea (a thin non-cellular layer).

They have a mouth that simultaneously acts as an anus; it is called a gastrovascular cavity. It means that hydra only have a single opening on their body, not just for consuming food, but also as a way for waste products to exit.

This combined part is surrounded by tentacles; each of them contains nematocytes (stinging cells).

These organisms do not have organs, but they do have tissues. It is composed of a tube around five millimeters in length, formed by ectoderm and endoderm.

It consists of two sections: the head part, which includes the mouth-anus and tentacles at the other end, and a foot and an adherent disk.

Interspersed between the cells of the epithelial layers are some multipotent stem cells. It results in 4 differentiated cell types, including secretory cells, gametes, nematocytes, and nerves.

Hydras can manage the amount of water inside their body. Due to this ability, they can contract or extend their bodies at will.

Another interesting fact is that they are responsive to light, despite not having sensory organs.

How Hydra Reproduces

Similar to planaria flatworms, another aquarium pest we discussed earlier, hydra can reproduce their population in two ways: sexually and asexually.

When food stock is plentiful, and the temperature is warm, ranging from 66-72°F / 18–22°C, they commonly reproduce asexually by budding. It appears as a budding growth on the parent’s body wall, then develops into a miniature adult hydra and separates into a new individual when it reaches maturity.

Under favorable conditions and with sufficient food, hydra can regenerate themselves every 2-3 days. It means they can create up to 15 new individuals in one month.

If the conditions lack food or are harsh, where reproduction is not possible in the asexual method, sexual reproduction occurs in hydra. In the wild, it often happens before the winter season comes.

An individual might produce female and male sex cells. A swelling that occurs in their body wall grows into the testes or ovaries. The individual with a testis will release gametes that swim freely into the water, then fertilize eggs in the ovary of another individual.

The inseminated eggs will be surrounded by a tough outer layer. When the parents die (due to cold temperatures or starvation), the resting eggs may fall to the base of a lake or pond in nature, or to the substrate or a surface in the planted aquarium environment.

Waiting for the more acceptable conditions, where they can hatch into larvae. Some species, like Hydra viridissma and Hydra circumcincta, may generate both ovaries and testes simultaneously, and are thus typically referred to as hermaphrodites.

Is Hydra Dangerous To Your Populations In The Shrimp Or Fish Tank?

According to the statements mentioned above, they only feed on small creatures. That means if your pets, such as fish, shrimps, snails, or crabs, are big enough, they are probably safe. However, if their numbers exceed hundreds or even thousands, they would overwhelm your population. For example, your fish may have a severe injury on their skin due to excessive stinging. If left untreated, it will lead to further problems.

Hydra can ingest an organism that is up to twice its size. The potential prey population in aquarium environments is shrimplet and fish fry. Their size is suitable for the hydra. Primarily, shrimp babies under 1 month old are at mortal risk.

They use neurotoxins to paralyze the victim. This poison is released from their tentacles or cnida (plural: cinade). Each tentacle is coated with cnidocytes or specialized stinging cells. The cnidocytes possess specialized structures known as nematocysts. It resembles a miniature light bulb with a coiled thread inside.

Cnidocytes contain a cnidocil or a short trigger hair that is positioned at the narrow outer edge of the cnidocyte. Upon the hydra’s tentacles coming into contact with victims, the nematocyst’s contents will discharge explosively.

Then, firing a thread like a dart containing neurotoxins into their prey or whatever triggered the release. This poison can immobilize their victims, particularly if nematocysts that shot in high amounts.

Hydra just needs less than 0.3 seconds to ‘stab’ its victims. Well, once some invertebrates, such as shrimp or scud, come close to these polyps, they will rapidly jerk away. It also happens to fish; they will suddenly swim away. A similar, hydra-like, and deadly parasite is also found in saltwater tanks, known as aiptasia.

In this case, aquatic plants are not significantly affected by the presence of hydra due to their predatory nature. But having many hydra inside your fish tank makes it unsightly.

Are Hydras Harmful To Humans?

The answer is obviously ‘NO’. Their stinging cells are too weak to be a threat to most humans. They will retract their tentacles quickly if you try to touch them. Nonetheless, if the stub is more than a thousand or even millions, it can cause harm to people’s skin. In a case, rashes on the fishers’ hands are caused by the combined sting of large hydra populations on the fishing net, which leaves it submerged in the water for an extended period.

Common Cause Hydra Appears In Your Shrimp Or Fish Tank

Like the ramshorn snails, they are introduced into your aquarium by hitchhiking on some live plants, decorations, equipment, substrate, wood, and stones from an infected aquarium.

Hydra can also arise in your shrimp or fish tank from the live foods, hardscape, plants, or soils you harvest from outdoor water sources.

It is crucial for aquarium keepers to ensure that the water from the fish bags purchased from stores does not enter their setup, as it may be a way for hydra to sneak inside.

How Hydra Eats

They are not active hunters chasing their prey. Instead, hydra are ambush predators that spend much of their time sitting and waiting for tiny organisms to come close, then launch a quick attack.

While waiting for its prey, the hydra could spread its body to reach its maximum length and gradually lengthen its tentacles. It is incredible and can be extended to 4 or 5 times the length of their bodies.

When getting maximum extension, their tentacles will maneuver slowly, waiting for contact with suitable prey. Once contact occurs, the stinging cells on their tentacles fire the neurotoxins while coiling the prey.

Within thirty seconds, their tentacles remain and join in order to conquer the struggling prey. After that, the tentacles will encircle them and move them into the hydra’s mouth aperture. This process usually takes around two minutes.

Approximately ten minutes after ingestion, prey are commonly swallowed into the body cavity, and digestion begins. After 2 or 3 days, the remains of their victims that can not be digested will be released from the mouth through the contractions.

If the organisms are too large to consume, they will discard them. In some cases, if the available food stock is insufficient, hydra can absorb organic molecules directly across their body surfaces to obtain a sufficient amount of nutrition.

If no food sources are left, they will stop reproducing and begin making their tissues for energy. Consequently, their body will shrink to a very small size, then die at the end.

How To Identify The Existence Of  Hydra In Fish Or Shrimp Tank

There are two methods to recognize the hydra inside your aquarium, that is:

By Their Look

Honestly, it is hard to notice the existence of a hydra at the beginning. Initially, they appear as tiny white spots resembling small, freely flying sand, eventually evolving into small, white, string-like structures.

Long identifying with your naked eyes is not enough to discern what they are in this phase. You require a magnifying glass and sit for a long time near your tank to get accurate information.

Once they start sticking on the glass wall or some surfaces with black color, showing “unfamiliar” shapes, catching your attention. Sadly, in the most similar case, the hydra population in this phase should already have spread in huge numbers due to their multiple faster habits.

Movement

These planted aquarium pests are typically sessile or sedentary, but they can occasionally move to find a more suitable location to forage. Hydra has two methods to move: somersaulting and looping.

In somersaulting, their body bends over, creating a new attachment point with their foot. Another method is to bend over and attach their bodies to the surface using their head part (mouth and tentacles), then move the disk foot.

Hydra can move to reach up to 10 inches in a day by using this two-movement method. At a glance, their movement resembles that of tiny worms.

To reach a long-distance area, they can perform an amoeboid motion. Hydra will detach itself from the substrate or surface, then let the water current take it to a new place in the fish tank.

How To Get Rid Of Hydra In The Shrimp And Fish Tank

Removing them manually using your hand is not recommended. Never try to break them with your fingers or squash them with your nails.

It only exacerbates the outbreak. Keep in mind that hydra can regenerate themselves, even from a small body piece. According to some research, they can continuously renew all their cell types. That means this ability can prevent them from experiencing the aging effects, essentially making them immortal.

Instead, we have prepared some tricks against them without a cure. It slightly works for minor to medium plague; let’s read:

Manual Removal

You can use a net with tiny holes or an aquarium siphon to remove them. However, this method is quite risky and only works for small infestations. Make sure not to damage them when you do so.

Cutting the Food Portions

Overfeeding is a common mistake that many aquarium owners make. This lousy practice will create a more complex problem. If you feed your aquarium pets with live foods such as daphnia, brine shrimp, micro worms, or bloodworms, some of them may become prey for hydra.

Although you provide dried conventional food, such as pellets, flakes, or algae wafers, the leftover food increases the populations of tiny organisms that hydra feed on. Additionally, hair or red algae may appear in this condition, exacerbating the issue in the aquarium. Utilizing food dishes effectively controls food scattering during feeding time.

Like other aquarium pests, the hydra is mobile if it has access to food sources. That means, if you reduce it, they will start to starve, and then their population can be controlled. It will take at least a couple of weeks to see the effect, and it is the appropriate long-term solution.

Adding Hydra Killers To Your Aquarium

Hydra themselves are a food source for certain animals in nature. In the aquarium habitat, some omnivorous fish, such as siamese algae eaters, paradise gourami, platies, betta, mollies, and guppies, as well as other fish that are willing to eat them, can handle the hydra invasion.

Unfortunately, these fish lead to other issues. If you keep some shrimps, they may wipe out the colonies. Instead, you can add one of the three reported snail types that can eat hydra: the Marisa cornuarietis snail, common pond snail, and asolene spixi snail. At least they are safer than fish, which we have mentioned before.

But do not assume that these snails only hunt hydra specifically. They just feed on anything they can eat.

Unfortunately, there is a possibility that they may also harm your plants. Well, do some research first, and ensure the hydra eaters you want to add fit with your setup.

On the other hand, having freshwater snails is beneficial. They can reduce the waste products in the aquarium by consuming them. That means the food sources for microorganisms are fewer, which is interfering with their population growth. It clearly impacts the hydra, where they lost their prey.

Raise And Lower The Temperature

You require a heater for this method. An abrupt temperature change may shock your pets; move them into a separate tank. Next, increase the temperature to 41-43 degrees Celsius (105-110 degrees Fahrenheit) for a few hours.

This treatment should not influence most aquatic plants. Remember, it can still be tolerated by most, and the period is not too long. Regardless, if you keep a highly valued or sensitive plant, it would be better if you take it out and relocate it to different containers of water.

Besides, you can lower the temperature by adding ice blocks. But they tend to go dormant rather than die. Upon the perfect condition being met, they will activate again.

Using Light Trap

This method may not remove all hydra in your fish tank. At the very least, it can significantly decrease their populations. You will need:

• Dim your aquarium lamp or switch off the light.
• Add a piece of glass, then stick it to the glass wall from the inside of the tank.
• Take a flashlight, point the light at these two layers of glass, and leave it in this condition for several hours.
• Hydras will move bit by bit, going to the light source and gathering there; at the end of the day, you can harvest them that sit on a piece of glass inside.
• Please take out the second attached glass carefully to prevent their fall into the water.
• Remove them from the glass altogether.
• Then wash the glass thoroughly.
• Repeat this process until you are satisfied.

Hydrogen Peroxide Treatment

This solution is familiar to most aquarists. It can solve many aquarium problems, such as eradicating most algae types, including GDA, GSA, spirogyra, oedogonium, cladophora, staghorn, and red spot algae. This product is also known to kill bacteria that live on the surface scums.

It turns out this liquid can suffocate the hydras, too. As you are aware, the utilization of this solution is hazardous and may harm your valued populations. You should relocate them before administering this treatment. This guide we get from a credible source, never overdosing:

• It is essential to know the water volume of your tank, measure it accurately, and consider the objects inside, such as substrate, decorations, equipment, and more.
• Next, switch off the filter system.
• Add 1.5 milliliters of 3% Hydrogen peroxide to 1 gallon (4.5 liters) of water, spreading it evenly across the surface.
• Stir the water softly to spread it.
• Leave it for about 1 hour.
• Switch on the filter system.
• In the same week, perform a water change.
• After that, add bacterial supplements to replenish the beneficial microorganisms that were eliminated during treatment.

For shrimp breeders, additional bacterial supplements are essential, as they can help regrow biofilms, which is beneficial for shrimp growth.

Aquarium Salts Treatments

Hydra are sensitive to sea salt or iodine-free table salt. You can add 2g of salt to 10 liters of water. According to a professional shrimp keeper’s site, 3-5g of common salt per liter of water for 3-5 days is still harmless for other aquarium inhabitants.

Other Medicine

Other cures that work in killing planaria are also potent in exterminating hydras. No-planaria, planaria zero, Panacur C, and canine dewormer are products that can be purchased on Amazon or at a local fish store. It has been proven to be effective in fighting against them. The dosage is similar to those worms; you can find out in “How To Identify And Eliminate Planaria Flatworms Inside Aquarium.”

How To Prevent Hydra From Appearing In The Fish Tank

They do not thrive spontaneously. Hydra is a stowaway that is often taken from external sources. Therefore, you should do this:

• Always purchase the in vitro live plants from trusted sellers.
• Inspect new plants carefully before putting them into the fish tank; it is recommended to soak them in a mixture of alum. You need one tablespoon of alum and one liter of water. Mix the solution and soak the plants in it for 10 minutes. Rinse them with fresh water.
• Quarantine every new animal from other sources before you add it to the aquarium.
• If you want to use soil, sand, driftwood, stone, or other materials you pick up from the wild, boil them in the kettle a few times. The alum mixture mentioned above can also be used to soak the hardscape or equipment from a separate tank. Then, rinse it well using plain water.
• Live food is rich in nutrients, but if you collect it directly from ponds or streams, there is a high risk of hydra or other parasites. Frozen food, culturing your own live food, or purchasing packed live food, such as brine shrimp, are more secure options.
• Ensure that you maintain your tank periodically to keep it healthy and stable.