Are Copepods Good for Freshwater Aquariums?

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Copepods are fast becoming a popular option for aquarium hobbyists all over the world. However, many who are first-timers keep asking – “Are copepods good for freshwater aquariums?”

Copepods are good for aquariums because they play a vital role in the aquatic food chain, as they form a vital link between microscopic algal cells to small fish and larger sea creatures like whales. Copepods purify the water. Copepods can eat diatoms and other phytoplankton. They are also eaten by bigger drifters, larva fishes, and filter feeders.

The answer to this is yes, copepods are good for freshwater aquariums. I’ll explain why during the course of this article, so keep reading!

What Is a Copepod?

For those who don’t know, copepods are tiny crustaceans that live in almost every freshwater and saltwater habitat around the globe.

“Cope” is a Greek word, and it means “Paddle”, while “Pod” means foot – Paddle-foot.

They have varying species, some are planktonic (they drift in seawaters), while some are benthic (live on the ocean floor). There are also continental species that live in limn terrestrial habitats, as well as other wet terrestrial environments. These include bogs, springs, ephemeral ponds, puddles, swamps, and damp moss.

Several species of copepods thrive underground in specific habitats such as freshwater/marine caves, stream beds, and sinkholes.

They have antennae and limbs which they use for movement in a similar fashion as paddles. Some species of copepods move in a scattered pattern, while others swim more smoothly.

Copepods do not grow large, the common length of adults is between 1 to 2 mm. However, adults of some species can be as tiny as 0.2 mm, and others could reach up to 10 mm.

Copepods play a vital role in the aquatic food chain, as they form a vital link between microscopic algal cells to small fish and larger sea creatures like whales.

The smallest copepods you can find look like specs of dust, and they live basically anywhere in the ocean. Their numbers are so large, it is practically impossible to count.

Copepods can eat diatoms and other phytoplankton. They are also eaten by bigger drifters, larva fishes, and filter feeders. It is believed that copepods are the most abundant single species of animal on Earth, as I have mentioned before, counting them is practically impossible.

How Much Food Do Copepods Consume?

One aquarium copepod can eat around 11,000 to 373,000 diatoms every 24 hours. This makes them very useful for controlling a diatom outbreak in the aquarium.

How Visible Are Copepods?

Aquarium copepods are small crustaceans, which makes them cousins of crayfish and water fleas. You can see them with your eyes if the water conditions are just right.

If the aquarium and the room are dark, and you shine a flashlight in it, you will see them attracted to the light, similar to the way moths are attracted to a porch light.

Many copepods live near the surface of the water, so you can see them better when they are in that position. The ones who love hanging out at the bottom will be less visible.

Their Physical Anatomy

Copepods are similar to other crustaceans, being that they have two main body parts.

  • The cephalothorax
  • The abdomen

They have ten legs, which they use for paddle-like swimming. They use their abdomen like a rudder, and it helps them direct their movement.

It may interest you to know that female copepods are larger than males.

How Many Can You Have In A Tank?

Aquarium copepods can occur in huge numbers, over 1,000 copepods can be found in one liter of water.

What Eats Copepods?

Copepods have their fair share of predators, and these include fish, amphibians, water fleas, rotifers, and various aquatic insects.

How Fast Do They Reproduce?

Calanoid copepods are known to take a few weeks to mature, and either spawn by shedding eggs or sperm into the water. They also brood their eggs in special brood sacs.

Calanoids can lay several dozen eggs in a day, which will sink to the bottom and hatch within approximately 24 to 48 hours.

What Do I Feed My Copepods?

You can feed them meaty foods that break down relatively fast in the water column. A nice mix of marine pellets and marine flake fish foods ground up in a mortar and pestle will give you desired results.

You can also culture phytoplankton in a 2-liter plastic bottle to feed your copepods.

Do Corals Eat Copepods?

Many corals will reap the benefits of the food that you feed your aquarium fish and invertebrates. Copepods, amphipods, brine shrimp, and mysis shrimp will also be eaten by many corals.

What Function Do Copepods Have in A Tank?

Tigriopus copepods are good water purifiers.

Their diet is broad, they will consume anything from algae spores to fish waste, and they will eat almost any kind of detritus.

For this reason, they’re excellent at keeping the water and the tank clean and free of gunk. Let them loose and they’ll go right to work, by filtering all the unwanted organic waste out of the tank water.

When Can I Add Copepods to My Tank?

You can start adding copepods to your aquarium when algae start to grow. By this time, they will have sufficient food in the tank. If algae are growing, then it means you’re at the end of the cycle and they will be just fine.

Do Clownfish Eat Copepods?

You may be thinking of adding some clownfish to your copepod-filled tank, or vice versa, but you’re worried about the safety of your copepods.

This will lead you to ask – Do clownfish eat copepods?

Well, the answer is yes, Clownfish eat copepods.

Once they are found to be abundant in their environment, clownfish are most likely to scramble on copepods, earning a significant nutritional value in return.

Some circles take full advantage of that, to the point where copepods are used as the sole source of feeding for clownfish.


As this article has pointed out, copepods are good for freshwater aquariums. Basically, they are good for any type of aquarium, being that they are a very adaptive species.

They also help the ecosystem of the tank, by eating up all sorts of organic waste from fish and other aquarium organisms.

I trust the information provided here has been helpful.

Take care.

Written by:

Pet Aquariums

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