Saltwater Aquarium Blog

How to Culture Rotifers: Batch Culturing Protocol

Culturing rotifers at home is fairly easy to do.  Rotifers are a great food source for newly hatched fish larvae and for some filter feeding invertebrates.  Ironically, the rotifers organism itself provides very little nutritional value to the animals that eat them. 
It is the content of their guts (the food they eat) that provides the nutrition.  As such, it is important to feed your rotifers with a highly nutritional food source, like phytoplankton.  If you’re serious about culturing rotifers at home, consider also culturing phytoplankton.  While it’s important to keep the cultures separate and avoid contamination, the skills needed to culture phytoplankton and rotifers are similar. For more information about phytoplankton culture, check out the phytoplankton page.

There are two popular ways to culture rotifers: as a continuous culture, or as a batch culture.  The following blog post will present the protocol I follow to batch culture rotifers at home.

Rotifer Batch Culture Set-Up and Protocol

• Cut 3 lengths of 12-inch rigid tubing and 4 lengths of flexible tubing: 3 long enough to reach from the bottles to the splitter and the fourth long enough to run from the air pump to the splitter
• Attach flexible tubing to splitter, pump and rigid tubing. Insert rigid tubing into culture bottle
• Turn on air pump
• Fill bottles with a small amount of freshwater to test and make sure all 3 airlines create a modest flow of bubbles. Adjust flow rate on the splitter as necessary to create uniform moderate flow.
• Empty the bottles and inoculate the first bottle with a starter rotifer culture
• Add a few ounces of phytoplankton, make sure aeration is on, and watch the culture over each of the next few days.
• When the water ‘clears’ to a light green tea-colored tint, and you can see little specs in the water when you hold the bottle up to a bright light, add a few ounces more phytoplankton.  Over a few days, by adding more  phytoplankton when the culture clears, increase the total culture volume to about ¾ of the bottle (about 1.5L
• After another 1-2 more days, once the1.5 liters of rotifers have cleared the phytoplankton, it’s time to start your second culture. Take approximately 1/3 of the culture (approximately 0.5L) of the tea-colored liquid and pour it into a second plastic bottle.  Fill each of the bottles to the top with phytoplankton.  In this way, the original bottle will be ready to harvest about a day before the second bottle.  Repeat this step to create as many culture bottles as you want. By varying the mixture of phytoplankton volume and rotifer culture volume (or density) you can optimize your cultures to be ready for harvest when you will need it.
• To harvest the rotifers, pour out about ¾ of the tea colored culture through a rotifer sieve (approximately 50-55 micron) and into a discard/water change bucket
• After you have ‘filtered’ ¾ of the culture through the rotifer sieve, turn the sieve upside down over second bucket (or small office-sized trash can dedicated to fish-room use), scoop up a cupful of the discarded culture water and pour it slowly over the upside-down rotifer sieve, effectively reversing the flow of water and rinsing the collected rotifers into your collection bucket/trash can. Collect the concentrated rotifers, feed them to your tank or store them in the refrigerator for later
• Fill the rest of the bottle (the remaining 1.5 liters), with fresh phytoplankton and start bubbling again

• Saltwater Aquarium Blog Tip: Instead of rinsing the rotifers from the rotifer sieve with discarded culture water, you can replace it with water from your display tank or with freshly made saltwater.  That way you can add rotifers to your display tank without adding, the impurities of the culture water. 
   
• Advanced Aquarist Tip: The key to surviving culture crashes—which you will have—is redundancy.  You always want to have multiple cultures working at the same time.  If you do, chances are good that at least a few rotifers from one of the cultures will survive. Just place the crashed culture(s) aside, get some new plastic bottles and use the survivors to seed a new batch.