How To Grow Copepods In A Refugium

Grow Copepods In A Refugium

Maintaining a healthy saltwater aquarium is all about creating a stable, self-sustaining ecosystem. There will be times, of course, when you will need to intervene, but it is important to create a system that is as naturally self-regulating as possible. This will save you time and money as you won’t be constantly adjusting the system manually.

Refugiums and copepods are an important part of a healthy system. Refugiums are either established in a separate tank that is hooked up to the main display tank or is included in the display tank but separated from the main part by dividers. Refugiums filter water by removing excess nitrates as the water flows through live sand, rock, and macroalgae.

Copepods provide further filtration in your refugium as they eat bacteria, detritus, and excess food that flows in from the main tank. Not only does this clean your water, but colonies of copepods also serve as a food source for several varieties of fish. Some fish like Wrasses and Tangs like to snack on available pods. Other fish like Mandarins, Sea Horses, and some types of Gobies exclusively eat copepods.

Growing these microorganisms in your refugium will allow your system to benefit from their natural water-cleansing effects and will help you save money if you do own fish that exclusively eat these small critters.

Using the Right Refugium to Grow Copepods

When looking at how to grow copepods you should start with the right kind of refugium, though there is no hard and fast rule for determining what kind and size of refugium to use. The general approach is the bigger the better, especially when it comes to growing copepods in a refugium. This due to the fact that copepod colonies need surface area to propagate. Most copepods stay at the bottom of the tank, though you can increase your surface area with porous rocks and certain macroalgae like Chaeto.

A small refugium is better than none, but ideally, you would have at least a 1:2 ratio – or ten gallons in your refugium for every 20 gallons in your main tank. Some refugiums are larger than the main tanks, especially if the display contains several copepod-eating fish. The more fish you have that eat copepods, the bigger you will want your refugium to be.

Setup the Refugium

If you are looking at how to grow copepods in refugium it is important to start with a well-setup system. Start by placing 2 – 3 inches of live sand at the bottom of the refugium. This could be special refugium starter sand available in various fish stores, or it could be sand from your main tank.

Next, add some porous chunks of live rock. This will ideally come from your main tank, or at least be the same type in your display.

The next step is to choose your macroalgae. As previously mentioned, you will want ones like Chaeto, Spider Algae, and Oar Grass that provide hiding places for your copepods and will filter nitrates from your water.

Once these steps are complete, add the water, ensure it is the same salinity and temperature as the water in your main tank, and let the sand settle.

Remove Predators from your Refugium

The only problem with using materials from your main tank is that predators can hitch a ride on rocks and in the sand, so be sure to remove any unwanted critters before adding copepods. The most common predators to look out for are emerald crabs and bristle worms. Wait for the sand to settle and the water to clear in your newly established refugium before removing these tiny nuisances.

Best Type of Copepods

When looking at how to grow copepods it is important to choose the right ones. Tigriopus Californicus are a large version of copepods that are usually used to feed adult fish. Their size makes them a more substantial meal and means that you won’t need your colonies to be as large in order to keep your fish fed.

These copepods are not a good idea for larval fish, though, as their large size means they can hurt or kill smaller fish. Tisbe and Nitokra are smaller copepods that are ideal for feeding small fish and filter feeders. They may be smaller than Tigriopus, but they reproduce faster and are just as hardy.

Introduce Live Copepods into your Refugium

You can buy live copepod colonies from most fish stores and from several online sites. These colonies usually come in bottles of 2,000 – 4,000 copepods. If your water’s temperature and salinity levels match those in the main tank, all you need to do is turn off your pumps and drop the copepods into the refugium. Leave the pumps off for about half an hour to allow the copepods to settle before turning the pumps back on.

If your main tank is not already established, you will want to purchase phytoplankton and add a few drops to your refugium. Ideally, your system will become self-sustaining and your copepods will live off of the impurities they clean from your water but you may, on occasion, need to add phytoplankton to ensure they thrive.


If you are trying to figure out how to grow copepods in a refugium, the good news is that it’s relatively easy. Growing Copepods in a refugium benefit aquarium systems by providing a natural enhancement to your filtration system and can be a self-replicating food source which can save you money if you have fish that eat copepods. To set up a refugium, go big with the surface area, add live sand, rock, and macro-algae, and add copepods when the water temperatures and salinity levels match your main tank.

Make sure there are no predators, add some phytoplankton to get your copepod colonies started, and you will have a self-sustaining, natural filtration system and fish food source going in no time.

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