Rotifer Culturing

Rotifer Culturing

This is a simplistic method of maintaining a live rotifer population at home. There are more sophisticated methods that can be set up once the basics have been mastered.

Rotifer Culturing is VERY EASY to do at home but have received a bad reputation in the past from people trying to grow rotifers using green water or yeast as feeds. These dead foods requires too much water turnover and typically only produce low densities due to fouling high ammonia and low nutritional value of the feeds in the water. Use a concentrated microalgae to eliminate both these problems.

Rotifers feed best on microalgae, typically in the 1 to 10 micron range. The most commonly used algae is called Nannochloropsis, a small green non-motile (non swimming) cell that is high in protein, carbohydrates, and lipids. Rotifers have a very high metabolism and need to eat every 4 hours.

Fortunately this is easy to do by keeping a supply of quality microalgae in the water with them.

Microalgae concentrates like NutriSpring Liquid 60 can be added to the water once or several times each day to maintain a healthy culture of rotifers. Simply add a few drops of NutriSpring Liquid 60 to the tank until you have a light green colour. If the tank still has a light green colour at the next feeding you are adding the right amount. If not add a bit more algae each time until there is a residual colour. The most common practice is to feed the rotifers in the morning and the evening.

Basic Components
20 Liter bucket or larger tank
Air stone (set on low)
De chlorinated salt water – Temperature 23-25 C is best with 19-25 ppt Salinity
Live rotifer culture
Microalgae (NutriSpring Liquid 60 or Lyophylized powder are the best)

Key Strategies
Keep enough microalgae in the system so that the rotifers never go hungry
Harvest at least 30% of your culture every day
Your rotifer culture system must be set up in a stand-alone tank – they cannot be raised in a reef tank or co-cultured with other organisms. Rotifers are planktonic (in the water column) so if your tank is in-line too many of your rotifers will be pulled out of the system.

Starting your culture
Place the rotifer starter culture in the bucket of salt water to allow it to acclimatise.
Wait 10 minutes then open the bag and slowly add the rotifer starter culture.
Add enough Liquid 60 to maintain a light green colour between feedings. Typically this will be 1-2 ml of Liquid 60 daily per million rotifers.
Harvest at least 30% of your culture each day after day 3.

Harvesting Your Rotifers to feed a Reef Tank
Before harvesting your rotifers stir the culture vigorously for 10 seconds. This will lift the detritus from the bottom, keeping the culture clean and running continuously for many months. This will not damage the rotifers at all.
Harvest 30% of your rotifer culture. This is best done by siphoning into a separate bucket and through plankton mesh of around 50 micron. Do not add the siphoned culture water to your aquarium as this will be high in ammonia.
Turn off your skimmer but leave your pumps running.
Place your rotifers directly into your reef tank.
Siphon water from your reef tank through the 50 micron plankton mesh back into your rotifer tank to replenish the water.

Harvesting Your Rotifers to feed Fish Larvae
Turn off your air stone for 5-10 minutes. This will allow the detritus to settle and the rotifers will float to the top. Harvest as many rotifers as you need by the same method outlined above. Replenish the culture water by the same method outlined above. If you don’t have a reef tank you will periodically need to clean your culture tank to prevent the detritus levels from building up and causing ammonia spikes.

Tips
Rotifers do not need any light and will do best in the dark
Do NOT let the rotifers ever run out of food. The survivors will take up to 24 hours to recover and start producing again.
It’s difficult to measure your rotifer densities without a microscope, so it might take 2-3 weeks before your find an equilibrium in your system for how much algae to feed and how many litters of rotifers to remove each day without affecting your culture densities.