Home » Aquarium Guides » Water Mites In Fish Tank | Are They Dangerous? ( Probably! )

Water Mites In Fish Tank | Are They Dangerous? ( Probably! )

Keeping a fish tank is fun and satisfying until you find some bugs in your aquarium. These disgusting creatures can make your aquarium less enjoyable. What are these water mites in fish tank, and do they harm your aquarium life?

Let’s find about these tiny critters in this article. You will also learn how to get rid of them easily.

Water Mites In Fish Tank

What are these water mites in my fish tank?

Most of the time, these tiny white mites are amphipods, copepods, ostracods, or daphnia. These creatures are common in the wild and often can be seen in closed aquarium systems too.

Usually, these mites are helpful to maintain the aquarium ecological balance. But if they grow exponentially or reproduce rapidly in the tank, it is a problem.

Water mite types


Amphipods are small crustaceans found on the bottom of the fish tank. They are usually red, green, or brown in color and often invisible to naked eyes.

When amphipods are present in large numbers, they can eat the eggs and baby fish of the community tank.


Copepods are also small crustaceans that grow up to 0.2cm. Also known as cyclops, these tiny critters are one-eyed and funny-looking.

They often exist as a small group on the glass or gravel of the fish tank. You can see them more easily whenever you clean the aquarium.


Ostracods are shrimp-like creatures that live in open water. Also known as seed shrimps, these critters are larger than copepods and grow up to 0.2cm in length.

These water mites are extremely resilient and can not be killed easily using fish medications.


Daphnia is often seen in the form of water fleas. They not only look like tiny crystals but also reproduce very fast.

They can easily cover the bottom of your fish tank in just a short time. You can recognize them easily by their jerky, vertical swimming style. They are entirely harmless and are useful as a first food for fish fries.

Water Mites In Fish Tank

How did these water mites get into my tank?

Water mites do not grow naturally in a closed aquarium system. They must be introduced to the fish tank by you.

For example, when you transfer live rocks or corals to the tank, they can bring in these mites with them. Also, if the water from a local pond or lake is used to fill up your tank, it can also bring these mites.

These hitchhikers can also come with new fish, plants, or other aquarium additions.

Most water mite species live in all aquatic ecosystems, including ponds, rivers, and oceans. However, amphipods are usually found in saltwater habitats.

If you don’t quarantine new fish and plants before adding them to your aquarium and if you don’t clean the decorations and equipment thoroughly, you may introduce water mites in your tank.

Are water mites harmful?

If the population of these tiny critters is low and does not reproduce rapidly, they are harmless.

But if their population grows exponentially due to the lack of natural predators in your tank, you may experience problems.

For example, water mites can destroy your live sand and cause a sudden drop in the tank’s pH level.

Some species can eat up healthy bacteria, which help maintain the aquarium’s biological balance. Water mites can also feed on small fish, and they may carry some parasites or diseases harmful to your pet fish.

What makes these bugs harmful to my fish?

These tiny creatures may not harm your fish directly, but their presence can make your tank look bad.

Besides, if they reproduce too much in the tank, they can reduce oxygen levels and starve your fish to death.

Occasionally, these mites bring in some deadly parasites and diseases with them. Fish can get infected by these diseases if they eat these mites or get their skin punctured by the sharp claws of the critters.

The presence of these creatures in the fish tank is not a problem as long as their population remains low. But if the population of water mites starts to increase, you must remove them immediately.

What causes these water mites to multiply?

Water mites are usually a part of a healthy aquarium, and people often let them live in their aquariums.

This is because their fish get access to free and nutrient-rich food. But if their population starts to increase rapidly, you’ll have to get rid of them.

Water mites population usually goes through three growth stages.

You won’t see any water mites in your tank during the first stage because most of them hide inside decorations and filter chambers.

But the number of these insects inside the tank starts to increase over time as their natural predators are not present in your fish tank.

During the following two stages, their population increases exponentially, and you will start to notice their whitish trails all over the aquarium.

You may also notice mites crawling on your plants and fish. This often happens when the water temperature is slightly warmer and when you overfeed your fish.

As you feed your fish more, the leftover foods and debris collect at the bottom of the aquarium, which means enough food for the mites to reproduce rapidly.

In the last stage, their population decreases as they start to die out from old age or starvation. If you remove or kill some of these mites, it can slow down their reproduction and eventually cause their population to dwindle.

How to get rid of water mites in a fish tank

Once the water mite population has increased rapidly, they may lower the tank’s oxygen level and starve your fish.

If you see some trails on the glass walls or on plants and decorations, you need to remove them from your tank.

You can get rid of these mites in several ways.

  • Reduce the feedings of your fish
  • Introducing “pod” eaters to the aquarium
  • Installing a powerful HOB filter

Reduce the feedings of your fish

The main cause of a sudden rise in the population of water mites is overfeeding your fish.

If you see your fish are not eating everything you give them within 3 minutes, just cut down on the feedings to control the mites population.

You can also provide food in an automatic fish feeder to keep their food intake under control.

Introducing “pod” eaters to the aquarium

Most carnivore and omnivore fish species love to snack on water mites. But some predators exclusively depend on “pods.” We call these species “pod” eaters.

You can introduce these predators to the tank, and they will hunt down water mites for you.

Installing a powerful HOB filter

If you have a powerful HOB filter, you can simply suck up some water mites with the help of its strong flow.

One advantage of installing a HOB filter is that you don’t have to remove the water from your aquarium. But this method is not as effective as it only removes a portion of the mites population.

How to remove water mites manually?

To get rid of them manually, you need to remove the mites from the fish tank physically. Here are some methods to do this:

  1. Using a turkey baster or a siphon pump – This is one of the easiest and most common methods. Try to siphon water mites into a bucket or trash can filled with aquarium water. This way, the mites will be automatically removed from the aquarium.
  2. Using a paintbrush or an old toothbrush – This is another simple way to get rid of water mites manually. You will need to take a paintbrush or an old toothbrush and scrub the glass walls of your fish tank.
  3. Using a cotton swab – This is another easy way to remove water mites manually. Dip a cotton swab into tap water and start scrubbing the glass walls of the fish tank. This way, you won’t have to remove any aquarium water, and your mites population will be reduced gradually.

However, this method is not as effective as the previous two, especially if you have a large fish tank.

“Pod” eaters for the fish tank

As mentioned above, some fish species are especially good at reducing water mites from a fish tank.

These “pod” eaters swift through sand and pick through rocks and other decorations to grab these critters to snack on them.

However, we must warn you that some of these species are extremely hard to care for and need expert-level knowledge to keep them alive. 

Here are some of these species that you can add to your fish tank:

  • Wrasse
  • Seahorses
  • Mandarin Fish
  • Sand-Sifting Gobies
  • Firefish
  • Angelfish
  • Crabs
  • Shrimps
  • Some soft coral species

Some of these species, like the Mandarin fish, exclusively depend on “pods” and need a constant supply of water mites for them to survive.

So, you might have to actually grow these water mites in another tank if you want these fish to thrive in your aquarium.

How to prevent water mites in a fish tank

There are several options for preventing water mite infestation in the tank. You can

a) quarantine all the new fish and plants 

b) Clean equipment using salt water, vinegar, or hydrogen peroxide 

c) Use a water mite chemical

a) Quarantining new fish and plants

Always quarantine new fish or plants before adding them to your fish tank if you use this option. Use a quarantine tank and only transfer the new fish or plants to your main tank after at least two weeks.

b) Cleaning equipment using salt water, vinegar, or Hydrogen Peroxide

If you add any equipment and decorations to the tank, you can use this option. First, make sure all decorations in your tank are well rinsed in fresh water and dried before adding them to the tank.

Clean all your decorations and equipment, such as canister filters, protein skimmers, and pumps with saltwater/ vinegar/ H2O2 before adding them to the aquarium.

This will kill any surviving water mites in your decorations or equipment before adding them to your aquarium.

c) Using a water mite chemical

You should use this as your last option because this might harm your aquarium life too.

Some chemicals like SL-Aqua Bio Protector Z1 and Fenbendazole can kill certain types of bugs, but these can kill your fish, shrimps, and snails too. Therefore, we recommend using this option when all other options fail.


Water mites are a huge problem for many aquariums worldwide, and it is important to keep them under control.

Although manually removing water mites from aquariums is hard, there are some simple ways that you can use to reduce the number of these critters in your fish tank.

Some fish species like Mandarins can keep water mites under control, but you need to know what you are doing before adding them to your tank.

Remember, these fish exclusively need water mites and can’t survive without them.

Water mites are extremely resilient and can survive even after cleaning your tank or decorations. Therefore it is important to quarantine all new fish and plants before adding them to your tank.

Credit to: dmichaels fish den
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About Dr.Chamika

Hello, I'm Dr. Chamika. I am a Researcher in Water quality, Aquatic organisms, and Environmental chemistry. I am a passionate fish keeper, with10 years of experience. My mission is to help other aquarists experience the joy of fish keeping.