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Rotifer Culturing
Last Updated: 12/07/2013
This is a simplistic method maintaining a live rotifer population at home. There are more sophisticated methods that can be set up once the basics have been mastered.

Rotifers are VERY EASY to culture at home but have received a bad reputation in the past from people that try to grow them using live algae or artificial feeds. Live algae requires too much water turnover and can typically only produce low densities due to the small volume of algae in the water, and artificial feeds will quickly foul the culture. Using a microalgae concentrate eliminates both of 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 microalgae in the water with them. Microalgae concentrates like Rotifer Diet can be added to the water once or several times each day to maintain a healthy culture rotifers. Simply add a few drops of Rotifer Diet to the tank until you have a light green color. If the tank still has a light green color at the next feeding you are adding the right amount. If not add a bit more algae each time until there is a residual color. The most common practice is to feed the rotifers in the morning and the evening.

Basic Components
20 Litre bucket or larger tank
Airstone (set on low)
Dechlorinated salt water – Temperature 25-28 C is best with 20-25 ppt Salinity
Live rotifer culture
Microalgae (Rotifer Diet the best)

Key Strategies
Keep enough microalgae in the system so that the rotifers never go hungry
Harvest at least 33% 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 seawater to allow it to acclimatise.
Wait 10 minutes then open the bag and slowly add the rotifer starter culture
Add enough Rotifer Diet to maintain a light green color between feedings. Typically this will be 2-3 ml’s of Rotifer Diet daily per million rotifers.
Harvest at least 33% 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 33% of your rotifer culture. This is best done by siphoning into a separate bucket and through plankton mesh of around 10 micron. Do not add the siphoned culture water to your aquarium as this will be extremely 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 10 micron plankton mesh back into your rotifer tank to replenish the water.

Harvesting Your Rotifers to feed Fish Larvae
Turn off your airstone for 2-3 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.

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 liters of rotifers to remove each day without affecting your culture densities.

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