What Are the Little Black Worms in Pond Filters? What You Need to Do

Have you observed your pond filter well, and you see little black worms in it? Do you think the filter is breeding worms? Do you have to dispose of these worms from your filter and pond? I will be talking about these little worms in this article. Read on!

The little black worms you see in your pond filter play a vital role. These black worms break down and feed on the filter’s organic waste, keeping them from getting into the tank. In short, these worms keep your pond free of organic waste and maintain good water quality.

These black worms can also lay eggs that might end up on your aquarium floor so I recommend you use a aquatic vacuum (Available on Amazon) every few weeks to such up the eggs and make sure they do not hatch.

What Are the Little Worms in My Pond Filter?

The little worms in your pond filter serve a great purpose for your fish and other aquatic life in your pond. These worms, known as blood worms, are relatively harmless to your fish, plants, and other aquatic lives. They can also serve as fish food to make a good treat for your fish.

These worms are in your pond filter for a purpose; they help in decomposing organic waste. The filter performs the important task of keeping the water quality clean by sucking in water, filtering it, and returning the water to the tank. As the filter does this, it collects organic waste and stores it in its tank where the worms are.

When the organic wastes get to this place, the worms start to work on it, decomposing and feeding. They feed on the decaying organic wastes, keeping your filter and pond free from toxins and other toxic matters. If the worms are not there, the organic waste will keep accumulating in the tank, causing trouble to the filter, pond, and aquatic life.

It will either cause your filter to malfunction due to congestion or cause toxins to develop in the pond. Neither of the results is suitable for your fish and other aquatic lives. It will help if you do not underestimate the essence of these worms.

How Did the Little Worms Get in My Pond Filter?

These little worms, blood worms, get into your pond filter through their parents. Blood worms are offspring of midge flies, the larva stage of the non-biting kind of midge flies. They get into the pond filter when midge flies lay their eggs in the pond.

Midge flies lay their eggs in safe places to keep their larvae offspring from fish and frogs. When the eggs hatch, they evolve into bloodworms. These creatures look for a safe place to stay and eat till they develop to their next stage.

They look for solid structures to hang on while food floats by and they eat. In searching for a haven, they get into your pond filter where you see them. You can also notice them in your pond, but these are not safe as they will serve a meal to your fish.

Having them in your pond filter or pond is not bad as they serve a double purpose. The worms help decompose organic waste and serve as food for your fish. Once the midge fly lays her egg, you should be expecting the little worms soon.

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How to Remove the Little Worms in My Pond Filter?

Although these little worms are not bad for your fish, they can create an unpleasant scene in your pond. You might not want them in your pond, especially if you pay attention to the beauty of your pond. You can get rid of these little guys from your pond in numerous ways.

  • Manual removal: Manual removal includes scraping off the worms from structures in the pond and filter. You will also need to perform regular cleaning of the pond’s water. You can also use aquatic vacuums to remove the worms and eggs from the pond and filter.

You can also use nets or skimmers to remove worms that float in the pond. You might also need to prevent midge flies from coming close to your pond to avoid further troubles.

  • Use of chemicals: You can also use licensed chemicals to get rid of the worms in your pond and pond filter. These chemicals will do a great job in removing the worms but can also be harmful to your fish. You have to be careful when applying them.
  • Biological removal: The biological control of bloodworms includes predators’ use to get rid of them. It is a natural method of removing the worms from your pond and pond filter. Several fish feed on bloodworms that you can introduce to the tank.

You can introduce bottom feeders to the pond like catfish, koi, etc., to feed on the worms. They might not have much access to the filter, but they will do a good job of keeping the tank clean of them.

How to Get Rid of Pond Parasites?

Pond parasites can be harmful to your dishes and other aquatic lives. You have to get rid of them before becoming unbearable for your fish. The kind of parasite you have in your pond will determine the method you will use to eliminate them.

One way to get rid of pond parasites is to use a broad-spectrum remedy. It will perform an efficient job in removing parasites from your pond. You can also use chemicals like herbicides, algaecide, parasiticide, etc., to get rid of parasites in the pond.

Performing constant change of water will also help control pond parasites. Maintaining good water quality will reduce the chance of parasites in your pond.

Preventing Little Worms In My Pond Filter?

Preventing little worms from getting into your pond is very simple. You have to get rid of the source, and you will have little or no problems with worms in your pond. Find a way to prevent midge flies from getting into your pond, and you have successfully prevented worms.


The little black worms in your pond filter are bloodworms. You might think they are harmful to your fish, but they are not. They provide your fish and pond with many benefits.

John Brandon

John has kept fish all his life (since he was about 5). He started with keeping guppies and fell in love with fish keeping almost straight away. That was 40 odd years ago. These days John still keeps fish and currently has two large tanks where he keeps many different types of fish such as Angelfish, Neon Tetras, Goldfish, Guppies and many more.