Rotifer Batch Cultures
Rotifer Batch Cultures
Culturing rotifers with a batch culture technique is akin to a manufacturing process. Instead of focusing on creating a stable environment to keep a relatively low-density culture thriving over a long period of time, the objective of a batch-produced culture is to maximize the yield of the culture over a short period of time. With a batch culture, you start the culture at a low density and feed them enough to allow them to proliferate to their maximum density. The density achieved is greater than in a continuous culture because the it is maintained only for a short period of time before the cutlure is restarted. The trick is to harvest the rotifers at their peak density and restart the batch. In this fashion, the rotifers are continuously reproduced, but at a much higher density. As such, you can maintain a lower culture volume yet produce a higher number of rotifers.
I culture rotifers in a 2L juice bottle, but you can use any size that suits your space and culture needs. The batch culturing process is fairly straightforward. Begin with a small starter culture. I fill the rest of the bottle with Nannochloropsis phytoplankton. I insert the airline tube and watch. Over the next few days (3-4) the culture water will transform from a dark, robust green to light green, to yellow/light brown. If left alone for another day, the water will clear, except for the rotifers, which will appear to be tiny ‘specs’ visible with the naked eye.
For maximum nutritional value, harvest the rotifers while the culture is still tinted light green. The rotifers themselves carry very little nutrition. However, the phytoplankton inside their digestive tracts is highly nutritious. So the rotifers will provide the most nutrition for your reef tank or fish larvae when their guts are packed with nutrients.
Advantages of Batch Rotifer Cultures
- Rotifers are produced at the highest densities possible.
- Since the majority of the culture volume is turned over every few days, crashes are less of a risk
- Maintenance is only required a few times per week, depending on how many cultures you are running and what the timing between harvest of each culture
Disadvantages of Batch Rotifer Cultures
- The culture must be harvested within a day or two of reaching the top density, if not, the culture will run out of food, oxygen and crash
- You will definitely need multiple (redundant) cultures unless you plan to harvest just one day a week
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