Water fleas in aquariumWater fleas in the aquarium are one of the common critters you can find floating around with your fish. If you’ve never heard of them, we are here to provide insight and help you out understand where they come from, what they are, and what they’re doing in your aquarium! So, read on to find out more about them.

What Are Water Fleas?

Water fleas in aquarium are small Cladocera from the phylum Arthropoda and subphylum Crustacea species, and are mostly the Daphnia types, also known as ‘Simocephalus Daphnia,’ so we’ll be discussing those.

Moreover, there are many types of fleas but the ones that are most commonly found around are Daphnia, Moira, Springtails, etc.

How To Get Rid of Excessive Water Fleas in Aquarium

Water fleas in aquarium are useful but some people detest them due to their overpopulation tendencies. If you’re one of them and want to get rid of these fleas, then we have a few tricks for you which can help you get rid of them. These tips are simple and easy to follow. Let’s discuss them one by one:

– Use Blanched Zucchini

The simplest trick in the book is to use a blanched zucchini. Put it in your tank overnight and leave it there. The water fleas will feast on it and attach themselves to it. In the morning, you can scoop it up and get rid of your fleas swiftly.

– Clean Them Out With Biological Cleaners

There are certain cleaners available that help in the thorough cleaning of an aquarium, and they are biological. Get yourself one of those and mix it with aquarium water in the right proportions or according to instructions on the bottle. They are effective and kill fleas instantly.

– Let The Fish Feed on Them

Sometimes, the water fleas in aquarium are sources of food for small fish. What you can do is feed the fish a bit less than you usually do for some time and let them feed on the critters. Within a day or two, you’ll observe a visible difference. However, this process takes time, and the fish are not likely to eat them up quickly or at all.

– Increase Ammonium and Nitrate Levels

There is a certain ratio of ammonium and nitrate levels in the water of an aquarium. When it is increased from that specific ratio, it becomes dangerous for fish and other creatures alike. So, if your water flea situation is out of control, you can increase your ammonium and nitrate levels. The only issue is: you have to transfer your fish to another container till the water is favorable to them and the fleas have all perished with increased chemicals.

– Change the Water

Another tip is to change the water of your aquarium. The process is a long one, you’ll have to start by taking out your fish and placing them elsewhere for some time. Then, you’ll take out the water containing fleas and fill the aquarium with a fresh batch.

You have to be extra cautious when doing this because fleas can attach themselves to fish and plants and they will repopulate in the temporary tank you place your fish. In the original tank water, however, with no source of food or anything, they are likely to die.

– Change Your Filtration System

Most of the time, these fleas can be found in the filters where they constantly reproduce and hence invade the aquarium. So, if our tips above don’t work, you might want to have a look at your filtration system. Have it fixed or removed and you’ll notice a clear change.

– Give Your Water Fleas in Aquarium to Someone Else

Some people look for ways to breed daphnias, mainly because these fleas are a source of filtration, food, and keeping the system intact when their numbers are controllable. These people also have fish that want to feed on these critters because of their high protein levels. As a last resort of sort, you can find these people, contact them and hand your fleas over to them.

– Scoop Them Out

Lastly, if the water fleas in aquarium are minimum in numbers, you can just scoop them out one by one.

They all rise above the water surface for a breath of fresh air. This happens lots of times during the day, so all you can do is just catch them when they rise above and dispose of them.

– Use Flea Nets

There are certain thin and white nets available in the market and online specifically for water fleas. You can keep such a net in your aquarium and the fleas will gather around it, get caught in the net, and you can then pluck the net out. It is so thin that it won’t bother the fish but will catch the fleas in slowly but effectively.

Ecological Conditions and Water Fleas

Ecological conditions and water fleas

Water fleas have an important role to play in ecology. They work as a filtration system, meaning they clean the environment from unwanted algae, bacteria, moss and other things that have the potential to harm it. In a tank, garbage does accumulate from time to time; Sometimes, they are the reason these water fleas find their way to the aquarium.

Advantage of Water Fleas at Times

Water fleas in aquariums are also useful at times because they get rid of the unwanted substances floating about in the water and keep it clean for the rest of the fish and other sea animals.


1. Are Water Fleas in Aquarium Beneficial?

Yes, the water fleas in aquarium are beneficial when their numbers are controlled. As discussed above, they act as filtration systems for any water body in which they currently live.

In the case of an aquarium, these critters are responsible for a clean tank, ridding it of unwanted bacteria, algae and even fungi. The fish remains or any other shedding skins of a crab, lobsters, snails or shrimps, etc. are all sources of food for Daphnias that keep the water fresh and clean by consuming them.

2. Are Water Fleas in Aquarium Harmful?

The answer to this is slightly complicated. Since we already covered the beneficial process of the critters, logically there shouldn’t be any catch. However, everything in nature works in a balance and so, these critters can cause damage in an aquarium too.

They do make the water ideal but when such conditions are achieved, they don’t leave. Instead, they infest the water with their eggs causing it to overpopulate which makes it difficult for fish and other creatures to live properly in the tank.

3. Where Do Water Fleas Come From?

Water fleas are commonly found in vernal pools, attached to certain plants, rocks, or even fish. They mainly live in freshwater but are known to survive harsh temperatures as well. In an aquarium, these foreign species come from a variety of sources: plants, fishes, other crustaceans, rocks or whatever else they can get attached to. They are microscopic so chances of seeing them properly with a naked eye are zero when they are just eggs.

4. What Are Their Characteristics?

The Daphnias are mostly found in shades of brown and white colors. They have a carapace covering most of their body; a carapace is a type of shell that protects such small creatures and their bodies from external harm. The feet of these critters are away from the shell which can help them move freely in the aquarium. Also, they have two antennas and can swim in a hoppy or jerky motion.

5. Can You Give Me Information about Water Fleas in Aquarium Reproduction?

You should first know that the water fleas in aquarium are both of sexual and asexual nature. Depending upon the circumstances, sometimes the female will turn themselves into male and help in fertilizing the eggs that usually requires a male.

Saying that, most of the time, the reproduction is parthenogenetic, which means that the female will fertilize the eggs herself and keep them in a brood pouch till they’re ready to hatch. That’s how the female produces baby female water fleas which are completely identical to the mother; this process is also named cloning.

6. What Is the Lifespan of Water Fleas in Aquarium?

The exact life span is unknown but they reproduce quickly and in huge numbers which allows them to invade a specific area swiftly causing problems. As discussed above, water fleas in an aquarium can survive even the toughest temperatures; this allows them to live relatively longer than other bugs.

In an aquarium, the water conditions have to be ideal which is why they are quickly invaded by these water fleas when the conditions are suboptimal.


Water fleas in aquarium are natural creatures inhabiting the water. In this article, we have provided you with all the information needed to understand their existence, their advantages and drawbacks, so here is a summary of it all:

  • The water fleas are sometimes bought by the owners intentionally for adding an aesthetic look and for sources of food and filtration
  • They are highly rich in protein so fish eating them are healthy and have glossier skin
  • These fleas are responsible for not letting any extra bacteria or algae in the water so that it remains habitable for a long time
  • They become a problem when their numbers grow and for that, we have given you solutions so if their numbers get out of hand

If you spot a water flea in your aquarium don’t fret from the beginning, as it is not necessarily true that it will infest your aquarium. Monitor them closely, and get rid of them if need be by using our guide.

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