How to Culture Rotifers to Feed to Your Live Coral or Fish Larvae

Rotifers are tiny invertebrates that often are raised as food for live corals and fish larvae. They are the ideal starter food for species of fish such as neon gobies and certain types of clownfish, which have tiny larvae with very, very tiny mouths. Rotifers can be fed to these fish larvae until the more easily available and more easily cultured baby brine shrimp will fit into their mouths. Rotifers also provide a wonderful source of nutrition for live corals and filter feeders.

However, buying rotifers to feed directly to your tank can be quite expensive. If you need more rotifers than for occasional feedings, I highly recommend raising your own. If you are a reef keeper already you certainly have the skills to do this! Compared to many aspects of saltwater husbandry, it is remarkably easy to culture rotifers.

You will want to buy your starter culture either at your local pet store or from a reputable online dealer. Be absolutely certain the rotifers you are buying are saltwater rotifers.

You will need:

Empty two liter soda bottles

Aquarium tubing

An aquarium gang valve

Small air stones

An air pump

Live, frozen, or powdered phytoplankton

Saltwater mix

Dechlorinated water

A plankton sieve, metal coffee filter, or paper coffee filters

Mix your saltwater according to the instructions on the packaging to a salinity of 1.018 to 1.019 using dechlorinated water and allow it to stand and aerate for 24 hours.

Fill a 2 liter bottle half full with new saltwater. Put in either one very small drop of frozen phytoplankton, enough phytoplankton powder to tinge the water green, or about two ounces of live phytoplankton. Live phyto is best but it is also the most expensive. I have used all three effectively. Live phytoplankton causes the least sediment and pollution.

Shake the solution well and add one ounce of rotifer culture or an amount of encapsulated rotifers per the seller's directions. Wet rotifer cultures take off a lot faster as they do not need to come out of dormancy.

Put the bottle in a warm location and use very gentle aeration such as a low powered air pump with a fine bubble air-stone.

If you use live phytoplankton, put the bottles in front of a good light source.

Watch for the tinge from the phytoplankton to start disappearing (several days at first) then add .5 liter of new saltwater (of the same temperature, PH, and specific gravity as the culture) with a new dose of food (live, powdered, or frozen phytoplankton) mixed into it.

To see if you actually have rotifers hold a very bright light behind the bottle and look for itsy-bitsy dots suspended in the water. They are pretty uniform to the naked eye.

Once you have a full bottle of rotifers split the culture in half and start a new 2 liter with the second half and add a dose of food mixed with water. As your number of culture bottles grows use a gang valve to split the air pump's output among your cultures.

You can now feed the rotifers to your reef tank.

The rotifers can be neatly separated from their culture water with a plankton sieve or in a pinch a coffee filter works just fine. You can swish the top of the filter in the tank you are feeding to add the rotifers.

If you plan to raise fish fry make sure you have many bottles of rotifers on hand. Fish larvae, especially clownfish larvae, eat an incredible number of rotifers every day.

I came up with these techniques from nearly four years of experimentation while attempting to raise Percula Clownfish larvae on a budget. Taking the suggestion of a pet store employee to raise my own rotifers if they were too expensive, some overheard remarks at a reefers meeting, and a vague memory from junior high general science I tinkered with varying salinities, different aeration techniques, different containers, and different amounts and types of feed in my cultures to finally arrive at this point. Feel free to experiment for yourself. You might stumble upon a better method of culturing rotifers through trial and error but the method detailed above should give you a starting point which bypasses many of the ineffective things I tried.