How to Get Rid of Aquarium Fleas

All right, you’ve got some fleas.

First of all, this is a bigger problem if we’re talking about your dog. Or, for that matter, yourself.

But if you see water fleas in your fish tank, you might be eager to learn more about what risks these little critterspose for your fish. And, of course, how to get rid of them.

So, let’s review the basic facts on water fleas: what they are, what problems or benefits they present, and finally how to get rid of them.

What Are Water Fleas?

a water flea is a microscopic shrimp that feed on algae and provides food for fish

Water fleas are members of the crustacean order Anomopoda. They form a large group, with about 450 species worldwide. Water fleas are typically found in freshwater habitats.

The most well-known water fleas are in the Daphnia genus. Daphnia occurs in ponds and streams throughout North America and Europe. Typically, in aquarium lingo, when we talk about water fleas, we’re referring to Daphnia.

A water flea is microscopic, only about .01-.12 inches in length. The body of most water fleas consists of the following parts:

  • A head with an antenna
  • A trunk and abdomen enclosed in a case called a carapace

They use antenna strokes to propel their bodies through the water. A water flea’s diet typically consists of algae and microscopic organic matter particles. The fleas themselves provide an important food source for many species of freshwater fish.

So, when it comes to your fish tank, are these little buggers friends or foes? Pests or pals?

Are Water Fleas Bad For My Aquarium?

“Having fleas” obviously sounds less than desirable. But are they a threat to your aquarium ecosystem?

First of all, let’s remember: Daphnia are not actually fleas. True fleas are wingless insects that feed exclusively on the blood of mammals and birds.

Water “fleas” are tiny shrimp. Well, not technically shrimp, but they are crustaceans. This means that they’re entirely aquatic. So, not to worry — they won’t be jumping out of the water anytime soon to feed on you and your land-based pets.

Concerning the health of your aquarium, let’s assess the potential threats. Here’s what we want to make sure the water fleas won’t be doing:

  • Directly harming or harassing your fish and other aquarium animals
  • Contaminating or otherwise damaging water quality
  • Affecting the aesthetic quality of your aquarium

Regarding aesthetics, you might not like the look of Daphnia swimming around in your otherwise pristine tank. They’re not the worst thing in the world to look at, but it’s understandable if you’d rather not see them.

Or, maybe you don’t mind a few but would rather get rid of them when they become too abundant. So, we’ll review how to get rid of water fleas below.

However, the good news is that Daphnia won’t cause any real harm to your aquarium. They aren’t bad for the water or the fish. In fact, lots of fish species will be happy to have them around to snack on.

Fish tank owners that didn’t intentionally bring in Daphnia are sometimes surprised to learn that they aren’t really a pest — they’re nutritious live fish food. Lots of owners choose to purchase or cultivate Daphnia.

Lots of other varieties of crustaceans and other tiny visitors are equally harmless to your fish tanks. If you see something unfamiliar, it’s always best to first identify it and then consider whether you’d like to eradicate it.

That said if you’d like to get rid of your water fleas, let’s discuss your options.

How to Get Rid Of Water Fleas in Aquarium

If it’s time to take care of those pesky water fleas, here are a few tried and true methods. They’re all relatively simple and can be put into action without too much time or expense.

Let Your Fish Do the Work

As your starter method, you’ll want to give your fish a chance to take care of your water flea problem for you. Give them a bit of time before you move onto other methods.

If you’d like to give the fish a bit of encouragement, skip feeding. This might help them notice the local food supply swimming under their noses. It will also slow down the influx of new organic matter that the Daphnia feed on.

Smaller fish tend to love feeding on Daphnia. You might choose to add some new smaller fish to your tank if your current roster isn’t taking the bait.

Water fleas are considered a tasty treat by many fish. However, if none of your tank residents take an interest, move on to some more proactive methods.

Change Your Tank Water

If you’ve got a thriving Daphnia community in your aquarium, that means that they’re finding plenty of things to eat. They’re feeding heavily on suspended particles of organic matter. They’re getting fat, and they’re making babies.

Changing your tank water will kill the fleas directly while also removing the food supply that would allow them to repopulate. You can siphon out the fleas and replace the current food-filled water with new water that’s clean and free of particles.

Just remember that water changes can be stressful and potentially dangerous to your fish. Don’t change all of the water at once, and follow standard recommendations for safe water changes.

To be sure you execute an effective water change that doesn’t harm your fish, check out our guide on Aquarium Water Changing.

Use a Biological Aquarium Cleaning Product

Biological tank cleaners help to reduce organic waste. Waste particles occur due to overfeeding or overcrowding — but there will be some amount of waste in healthy tanks, too.

These products are made to assist with your cleaning process. But they’re a helpful tool in your fight against water fleas because they help reduce their food supply.

Simply search for a product that is appropriate for your aquarium, and follow the instructions on the label.

Use the Blanched Zucchini Trick

The most famous home remedy for water fleas is the blanched zucchini trick. This is an interesting way to get rid of fleas that really works.

Use the Blanched Zucchini Trick

First, blanch a zucchini. Cut off a slice and insert it into your tank. The water fleas should be attracted to the zucchini, and they’ll attach themselves to it. Once you see this, simply remove and dispose of the zucchini.

The whole process shouldn’t take more than a few hours, but you might like to leave the zucchini in the tank overnight, then remove it in the morning.

Learn More About Maintaining a Healthy Aquarium

If you’re struggling with water fleas, we hope that you found this guide useful.

Remember that Daphnia is not harmful to your fish or your water quality. Even if they seem to be taking over, their presence is a minor issue and one that you can easily fix.

Dealing with some other unwelcome guests? We’ve prepared a similar guide for How to Get Rid of White Worms in an Aquarium.

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