Amphipods and Copepods 101: What’s in My Tank?


While you enjoy the aesthetics of your aquarium, you may notice a bug or two. The critters you see within your tank are most likely copepods and amphipods, and they provide numerous benefits for your fish and your tank’s ecosystem.

If you’re unfamiliar with these crustaceans and their benefits, take a look at this helpful guide and get to know your aquarium’s new additions.

What Are Amphipods?

Amphipods are invertebrate crustaceans without an outer shell and are found in many types of water sources. Amphipods are most commonly found in warmer, tropical waters. These crustaceans are a food source for fish, birds, and other invertebrates.

Amphipods are brightly-colored and easy to spot since they resemble shrimp. Finding them in your aquarium might take you aback at first, but they’re completely normal, if not beneficial.

What Are Copepods?

Copepods are a type of small crustaceans that live in freshwater and saltwater. These aquatic bugs are very similar to amphipods and exist nearly anywhere with water, even swamps and plants. Copepods are larger than amphipods and exhibit some of the same behaviors, but they lack a circulatory system, a tail, and gills.

Copepods live primarily on phytoplankton and are a source of food for bigger fish like anchovies. When copepods “bloom,” or increase in population, they make the water in the tank cloudy. These crustaceans are an abundant food source for your fish, especially when they bloom.

How These Bugs Affect Your Aquarium

Both copepods and amphipods are likely to show up in your aquarium at some point. These critters are extremely hardy and tend to withstand common disturbances.

However, seeing these bugs in your aquarium isn’t as bad as it seems. Copepods and amphipods provide several benefits for your aquarium.

They Provide Food

Copepods and amphipods are an excellent and abundant food source for your fish. They’re much more nutritious than traditional fish pellets and resemble real wildlife ecosystems for your fish.

They Provide a Healthy Ecosystem

Fish need a perfect ecosystem and water PH level to live a long and healthy life. With aquarium macroalgae, your tank gains added nutrients for your fish. Plus, macroalgae reinforces growth for copepods and help them reproduce, giving your fish even more to feed on.

Besides being a food source, copepods and amphipods work together to keep your tank clean from bacteria. They also take care of fish feces and other things that make tanks dirty.

They’re Easy To Get

You can purchase inexpensive copepods and amphipods in bulk. Considering the low cost, these critters provide an easy way to keep your fish fed and your tank clean. You can even buy these crustaceans online.

Caring for Your Aquarium and Its Critters

Your aquarium is a complex ecosystem that houses more than just your beautiful fish. With the help of some friendly and multi-tasking copepods and amphipods, your fish will continue to thrive in their new home.

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