What Are Copepods and Why Are They Important for Your Saltwater or Reef Tank?

When building a thriving saltwater or reef aquarium, one of the best-kept secrets to long-term success is creating a balanced, natural ecosystem. A big part of that? Copepods. These tiny creatures play a surprisingly important role in maintaining a healthy, stable tank—and they work even better when paired with phytoplankton.

Copepods are microscopic crustaceans that live in oceans, lakes, and reef tanks. Despite their small size, they are incredibly important in marine ecosystems. Think of them as your reef tank’s cleanup crew and natural snack bar all rolled into one.

There are different types of copepods—some crawl on rocks and glass, while others swim freely in the water column. In saltwater tanks, copepods tend to live in the sand bed, live rock, refugium, and crevices of your aquascape.

Here are just a few reasons why adding copepods to your reef tank is a smart move:

1. Natural Food Source:
Copepods are a favorite live food for many saltwater fish, especially mandarins, wrasses, gobies, and pipefish. These fish often struggle to thrive in captivity without a steady supply of live prey, and copepods can help meet that need naturally.

2. Algae Control & Cleanup Crew:
Some species of copepods feed on detritus, film algae, and leftover food particles, helping to clean up the tank and reduce waste. They can contribute to better water quality and reduce the need for excessive manual cleaning.

3. Biodiversity & Ecosystem Balance:
Copepods are a cornerstone of a natural reef environment. By adding them, you're helping to replicate the biodiversity found in the ocean, which supports the health and resilience of your aquarium.

4. Boost Refugium Performance:
If you have a refugium, copepods can populate it and thrive, creating a safe breeding ground where they multiply without being eaten. They’ll naturally migrate into your display tank and provide a continuous food source.

Phytoplankton are microscopic plants (or algae) that float in the water column and form the base of the marine food chain. While you might not see them with the naked eye, they play a vital role in your tank’s success—especially when you have copepods.

How Phytoplankton Help:

• Primary Food for Copepods:
  Copepods feed on phytoplankton. Regularly dosing live phytoplankton ensures your copepod population has a constant food supply, helping them reproduce and thrive.
• Nutrient Control:
  Phytoplankton naturally consume nitrates and phosphates, helping to prevent algae outbreaks and contributing to a more balanced nutrient level in your tank.
• Coral Health:
  Many corals and filter feeders also benefit from live phytoplankton. Dosing phyto can improve coral coloration, polyp extension, and overall vitality.

When used together, copepods and phytoplankton create a mini food web right in your aquarium. Copepods feed on the phyto, fish and corals feed on the copepods, and your tank benefits from better water quality, cleaner surfaces, and a more balanced ecosystem.

Whether you're trying to support picky eaters, reduce detritus, or add biodiversity, adding copepods and dosing phytoplankton is one of the best things you can do for your saltwater or reef tank.

We recommend seeding your tank with live copepods and regularly dosing with live phytoplankton. Not only will it help your tank look better and stay cleaner, but it will also promote the long-term health of your fish, coral, and invertebrates.

We use AlgaeBarn’s Live Copepods and Live Phytoplankton