Feed rotifers upon arrival, if you wish to use the rotifers as a single feeding we recommend feeding with Phyto-Feast. Allow 20-30 minutes for rotifers to feed. If you choose not to use the rotifers immediately, they can be kept refrigerated for several days. Lightly feed prior to refrigerating and feed daily if needed.
For maintaining a small culture of rotifers we recommend using Roti-Diet for daily feedings and the Phyto-Feast for enriching. When maintaining batch cultures, it is best to maintain multiple, minimum of 3, cultures. The 2.5 gallon dishpans available at most department stores work well. Wash well prior to using and make sure all detergent has been rinsed off. It is best to have one extra for maintenance purposes. Make up a supply of artificial saltwater, any inexpensive brand, 24 hrs prior to receiving your rotifers in a clean plastic garbage container. We generally keep our salinity at 5-10 ppt. Aerate well. After 24 hrs fill two of the dishpans about one-third of the way full with saltwater and lightly aerate. Add enough algae to lightly tint the water. Allow rotifers to reach room temperature. Once this is accomplished, split the bag of rotifers into the two dishpans. Go ahead and set up the third dishpan the same way and leave for the following day. The following day take around 500 ml from each dishpan and add these rotifers to the third. Now go ahead and bring all three dishpans up to within two inches of the rim and feed with algae once again. It will take another day or two for the density of the rotifers to increase to levels in which you can start harvesting around 30% of each bowl. Until then maintain a harvest amount of half that to suit your needs. Remember as your rotifer densities increase so will the amount of algae you need to maintain the cultures. To put this into context we use 50 ml of algae to maintain almost 40 gallons of rotifers daily. Around 10 ml of algae daily should be plenty to maintain three cultures of this size. As detritus starts to accumulate you will need to clean your cultures. There are two simple ways to do this: remove the airstones out of all the dishpans and allow detritus to settle. Take your clean dishpan and pour approximately 70% into the clean bowl, use the remaining 30% for your daily harvest. Clean the bowl and repeat until all three cultures have been cleaned. Top off each bowl with fresh saltwater and feed. Replace airstones. Or for better results and consistently clean cultures you can transfer and harvest into a clean bowl daily. Whatever your method, it is best to clean your cultures at least every three days.
Troubleshooting Culture Problems
Eventually you will have a culture crash, thus the reason for maintaining several cultures at once. Visually you can see a culture thinning out, if more then one bowl is going through this it is probably best to go ahead and get another culture. If you have the luck of being able to look at the rotifers under a scope it may help determine what went wrong. A healthy culture will be made up of all females, they are plump, usually carrying 1-2 eggs and at least 30% or more of the rotifers you are viewing should be carrying eggs. If this is the case back off on the quantity of rotifers you are harvesting daily or increase the amount of algae being fed. If you identify a bunch of skinny rotifers moving through the water column quicker then the females, you are looking at male rotifers and the culture is finished and needs to be restarted. Water quality has diminished to the point that resting cysts are being produced. If another organism, smaller then rotifers is observed, they are most likely ciliates. They do not directly harm rotifers, but they do stress out a culture by sheer density and because they compete for food. Ciliates do not usually appear in great numbers when cultures are being fed strictly algae, but when artificial, yeast -based diets are used, ciliate populations will explode. To remove most of the ciliates, remove the airstone and allow the culture to settle. Rotifers generally stay in the water column while the ciliates will settle to the bottom. After several minutes pour off the top 80-90% of the culture into a clean bowl and discard what is left. This may need to be repeated over several days. Other problems may include heavy aeration which will strip the rotifers out of the water, maintain the alkalinity above 80 mg/l, temperature should stay between 75- 82 degrees F for optimum reproduction, and the most common problem is just allowing them to run out of food.