Usually rotifers are cultured in freshwater tanks where they are kept for carrying valuable nutrients to young fry and filter-feeding invertebrates. But in saltwater tank too they can be highly beneficial to coral’s nutrition and growth. They are extremely small and multiply very quickly so they can become many in just a short period of time. The two frequently cultured saltwater types are of the L-strain and the S-strain, the S-strain being the smallest at about 150-220 microns in length.
Rotifers are the best starter food for species of fish such as neon gobies and certain types of clownfish, which have minute larvae with very small mouths. Rotifers can be fed to these fish larvae until the more effortlessly accessible and more simply cultured baby brine shrimp will fit into their mouths. However buying rotifers directly can be quite expensive so we recommend you culturing your own. Here is how you can raise them at home.
You will need:
- 3 to 5 gallon bucket or larger tank
- Dechlorinated salt water
- Temperature 25-28 °C/ 70-82 °F is best
- Salinity 10-35 ppt (Specific Gravity 1.0075 – 1.026), optimum 15-20 ppt
- Live rotifer culture
- Microalgae (Nannochloropsis-based feeds are best)
Keep enough microalgae in the setup so that the rotifers don’t starve. Harvest rotifers in a standalone tank and not in any reef tank.
Here is how you do:
- Put the bag of rotifers into the bucket and allow it to gradually warm up
- After 5 minutes open the bag and add the rotifer starter culture
- Add 7 drops of Nanno 3600 or 30 drops of Rotifer Diet
- Next add microalgae daily but wait at least 3 days before starting to collect them if it is desired to assemble up the population as quickly as feasible
- Add enough Nanno 3600 or Rotifer Diet to maintain a light green color between feedings. Usually this will be 2-3 ml of Nannochloropsis daily per million rotifers. Harvest at least 25% of your culture each day
To feed rotifers in a reef tanks
- Before beginning to collect your rotifers stir the culture briskly for 10 seconds. This will mix up the debris settled at the bottom, keeping the culture clean and running continuously for many months and will not harm the rotifers at all.
- Collect 25-33% of your rotifer culture. This can be done by scooping with a jar, or pouring the culture out of your bucket.
- Turn off your skimmer but leave your pumps running.
- Pour the ready rotifers directly into your reef tank. The water become cloudy temporarily until the debris settles to the bottom.
- Remove an equal amount of water from your reef tank. Pour it through a coffee filter back into your rotifer tank to restock the water.
To feed fry and larvae
- Turn off your airstone for 2-3 minutes. This will allow the debris to settle and the rotifers will swim to the top towards the light.
- Collect as many rotifers as you need by softly scooping them off the top of your tank
- If you have a reef tank follow the directions mentioned above
- If you don’t have a reef tank you will sporadically need to clean your culture tank to put off the debris levels from building up and generating ammonia. Use a modified version of the Reef Tank directions and either use or dispose of the rotifers.