1 How rotifers are cultured
1.1 One-time culture method
Culture tank: Use potassium permanganate at a concentration of 20×10-6 as a disinfectant solution, soak for 20 minutes and then clean the solution. Heating facilities: in the indoor pool culture, when the water temperature is low (below 20 °C), the electric heating facility is heated, so that the water temperature of the culture pool is controlled at 22 ~ 27 °C, so as to be suitable for rotifer proliferation.
1.2 Inoculation method
Add natural seawater filtered by sand filter or 250 mesh sieve sacks to the pre-prepared culture tank, and add chlorella and flat algae of suitable density, the water of the pond is pale green, and then inoculate with rotifers. The density of inoculated rotifers is preferably 100 to 150 pcs/mL, so that in the case of feeding chlorella or flat algae. The density of rotifers can reach 250 to 300 /mL at 2 to 3 d, and when the density of rotifers reaches more than 300 /mL, it is harvested and re-cleared and re-cultured. Oxygenation: In the experiment, the culture rotifers are not oxygenated, the culture effect is not good, and it must be oxygenated when cultivating rotifers at high density. It is advisable to fill one gas stone per 2 m2 of water, and the inflation amount is adjusted so that the water in the culture tank can just be rolled. Water residues or cement tanks must be sterilized with potassium permanganate concentrations of 20×10-6 prior to culture.
1.3 Water for cultivation
Filtered by sand or 250 mesh sieve tulle bags to avoid the invasion and reproduction of predators such as sword fleas and water fleas, and to inhibit the proliferation of rotifers.
1.4 Culture methods
Chlorella or algae are first cultured in a pool of water, and rotifers can be inoculated into the pool when the chlorella density reaches 1200×104 to 1 500×104 cells/mL or 25×104 to 100 ×104 cells/mL. The inoculation density is 50 to 100 pcs/mL.
1.5 Methods of preserving rotifers
Induction and harvesting of dormant eggs: at the beginning of the feeding of a large number of chlorella or flat algae into the rotifer culture tank, after 2 to 3 days of culture, suddenly stop feeding, stop inflating, a few days later can induce rotunda to produce dormant eggs. Ice is added to the pool to bring the water temperature from 30 °C to below 15 °C to obtain a body sleep. The dormant eggs produced by rotifers basically sink to the bottom of the culture pond, drain the pool water, and take the debris at the bottom to save.
1.6 How to save
Store in a cold, dark place, store in the refrigerator, at a temperature of 5 to 10 °C, add a little fresh water every 1 to 2 months.
2 Results
Using the method of high-density cultivation of folded arm-tail rotifers, the bait cost in the production of river crab seedlings was saved by 68,000 yuan, and the output was 1.2 times higher than that of other workshops.
3 Discussion
Water residues or cement tanks must be sterilized with potassium permanganate concentrations of 20×10-6 prior to culture. During the incubation process, it is necessary to observe diligently and pay more attention to the feeding situation. Feed 3 to 4 times a day, each feeding of chlorella or algae so that the water transparency of the pool water is 30 cm. In the case of insufficient algae, baker's yeast can be added to the feeding amount of 200 g of baker's yeast/million rotifers, and the whole water-soluble baker's yeast must be water-soluble and then evenly sprinkled and fed.
The cultivation of microalgae has an important nutritional effect on marine animals. Phytoplankton are the foundation of the marine food chain. Most marine invertebrates rely on microalgae throughout their life cycle. Microalgae can be used in aquaculture hatcheries for larval rearing of fish, shrimp and shellfish, especially for the rearing and nutrient enrichment of rotifers and euphorbia. Microalgae can also be used to perform the widely reported green water technique to improve fry growth, survival and feed feeding, and to develop the immune system, pigmentation and swim bladder function. It has also been reported that green water technology has a positive effect on stabilizing the water quality in aquaculture ponds.
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