Bug-tail rotifer cultivation method

The Rotifer is a group of tiny multicellular animals, with a wide variety, widely distributed in freshwater, brackish water, and sea waters. It is a major component of plankton in water, and an important natural food organism for fish and crustaceans. , has always been people's attention. Many studies have been conducted on the biology, artificial cultivation and application of rotifers. Among them, the brackish water type, Brachionus plicatilis (hereinafter referred to as rotifer), has the most in-depth research. It has strong viability and rapid reproduction. The characteristics of rich nutrition, suitable size and easy cultivation can be applied in the culture process of at least 60 marine finfish and 18 crustacean larvae.
First, the separation of rotifer species Rotifers first need to have a species of rotifers, species rotifers can be supplied by the relevant units can also be separated. Brachionus rotifers live in brackish water and seawater. When the water temperature reaches 15°C or more, they are found in small hydrostatic bodies such as small otters and small ponds in seaside high tide areas, especially waters with a relatively high quality of water and planktonic algae. The rotifer tail is often living. Available plankton nets with a mesh size of approximately 120 microns (ie, the coarse nets of general plankton fishing) are collected from these small bodies of water, preferably before the sunrise in the early morning when the rotifers move to the surface to better fish. First use 300 mesh nylon mesh filter out the small fish, debris, and then concentrate in the container for several hours. Using the characteristics of rotifers for resistance to anoxic or harsh environments, when the deaths of copepods and other planktons sink to the bottom of the water, gauze or filter paper is put on the surface to make the rotifers floating on the water layer adhere to it. Remove the gauze and rinse the rotifer into a separate container to obtain a more pure rotifer. According to this method, after 2 to 3 separates, pure rotifers can be obtained. The collected water sample can also be examined under a dissecting microscope. If a rotifer is found, use a micropipette to suck it out. To avoid mixing with other animals, place the aspirate water in a clean, concave slide and filter. After the observation is accurate, inhale in a test tube or a small Erlenmeyer flask. The individual rotifers are larger in size and can be easily separated by straws. The salinity of the original environment of the rotifer should be determined during the isolation process. The salinity of the rotifer water should be similar to the salinity of the original living environment. Because the endurance of Brachionus plicatilis against sudden changes in salinity is low, if it is necessary to change the salt culture after successful isolation and cultivation, it must undergo gradual domestication.
Second, rotifer dormant eggs and hatching rot species can be long-term culture and preservation, can also be long-term preservation of the form of dormant eggs. If the latter is used, the dormant eggs must first be hatched before cultivation.
1. Ambient conditions for dormant egg hatching For dormant eggs that are kept in dark conditions, light is a necessary condition for ending dormancy. The dormant eggs can hatch in the salinity range of 1.5 to 35 degrees, but the salinity of 15 to 20 degrees is most suitable. In the temperature range of 5 °C to 35 °C, dormant eggs can hatch, but the incubation time varies significantly with the temperature, the most suitable incubation temperature is 20 °C ~ 25 °C. At the same time, a small amount of Platymonasaurea or Chlorella sp. was added to the hatching container to make the water slightly pale algae, which is favorable for hatching.
2. Incubation method of dormant eggs In order to avoid the harm of predatory organisms, elimination of small crustacean, dormant egg hatching and culture of seawater of larvae need to be filtered with 300 mesh sieve net, and add fresh water to adjust salinity to the most suitable range. Various glass culture tanks and small aquariums can be used as hatchery containers. Before use, containers should be cleaned, disinfected, washed with filtered seawater, then added with hatching seawater, then a small amount of algae solution should be added, and a small amount of rotifer dormant eggs should be put into the containers. Hatching in seawater. There are a lot of algal residue mixed in dormant eggs, and too much water can cause bad water quality. The hatching container should be placed near the window or with artificial lighting. Stir the body of water 1 to 2 times a day during incubation. If conditions are suitable, hatching usually takes 3 to 7 days. There is a large amount of dead algae in the hatching tank, and the water quality is not good. The hatched caterpillars should be sucked into the standby culture container for culture.
Third, the culture method according to the culture conditions of human control is divided into extensive and intensive culture; according to the characteristics of culture and harvest is divided into one-time culture, semi-continuous culture and continuous culture, there is a large area of ​​soil pool culture. Here are two commonly used culture methods: semi-continuous culture and large-area earth-pool culture.
IV. Semi-continuous culture Semi-continuous culture is a common method for cultivating rotifers. The following describes a typical semi-continuous culture method using a cement tank as a culture vessel.
1. The culture tank is divided into two kinds: rotifer culture tank and monocytic algae bait culture tank, both of which are outdoor cement tanks. The capacity of the two tanks is approximately 1:2. The rotifer culture pond has a capacity of 30 cubic meters or 40 square meters and a pool depth of 1.4 meters (effective water depth of 1.2 meters). The single-cell algae cultivation tank has a capacity of 100 cubic meters to 200 cubic meters.
2. Cultivation of monocytic algae bait Wash rotifers and monocytic algae cultivation ponds, sterilize, irrigate, fertilize, and cultivate monocyanobacterial baits.
3. Inoculation When the algae bait reproduces to a greater concentration, 30 to 50 rotifers per milliliter of water are used to enter the rotifer culture pond.
4. After inoculating rotifers, inflate culture. In addition to the unicellular algae feeds in the feeding pool, the rotifers should also be fed with some baker's yeast, and the daily feeding amount is 1 g to 1.2 g of yeast per 1 million rotifers, which is divided into two or more feedings in the afternoon. . First add the yeast in the bucket and mix it with water and then pour it into the water. If it uses active dry yeast, use an electric stirring mill to whisk the pellets of yeast dry water into a separate yeast cell (in suspension in water). Refeed.
5. After harvesting for 4 days to 5 days, when the density of rotifers exceeds 100/ml, 20% to 35% of the water volume will be harvested each day. At the time of harvesting, a cage with a capacity of about 40 liters can be made from a screen mesh with a mesh size of less than 100 micrometers. The cage is 40 centimeters high and supported by a wooden frame outside. The cage is tied tightly within the wooden frame and opened. Put the cage and the wooden frame in a large plastic basin 20 cm high. Use a siphon to suck out the pool water and filter it into the cage. When the density of rotifers in the cage is large, use plastic scoop to feed as bait or continue to grow as a species of rotifer. Immediately after harvest, the algae was collected from the algae algae bait pool into the rotifer culture pond to make up for the recovered water, and continue to be fed to the yeast for aerated cultivation. A part of it can be harvested every day. As rotifer culture ponds such as baits, rotifer manure and other substances will increase as the number of culture days increases, so that the water quality gradually deteriorates, so each culture time can generally maintain 15 days to 25 days, up to 30 days, and then all Harvesting, clearing the pool, began a new round of training.
5. Large-scale soil pool cultivation Most of the fish and shrimp nursery sites in China have a certain amount of earthen ponds. The use of earthen ponds for cultivating rotifer technology is relatively easy to master. The cost is low, the harvest volume is large, and the quality of rotifers is good.
1. The location of the culture tank culture pool requires the convenience of drainage and irrigation. It is better to have a freshwater source in the high salinity area and adjust the seawater salinity when necessary. The size and number of culture pools are mainly determined by the needs of nursery production. The annual production of 200 million Chinese prawn shrimp nursery, with 4 to 5 rotifer culture ponds with an area of ​​1 mu to 2 mu. If the number of nursery is large, rotifers can also be cultured in shrimp ponds with an area of ​​10 mu to 15 mu. The bottom of the pool is preferably made of impermeable mud or mud sand. The bottom of the pool is required to be flat and the dike is strong. The effective depth of the pool is 1 to 1.2 meters. Pump power can be used to lift the water, and a 250 mesh or 300 mesh screen filter can also be installed on the gate. When the tide rises, seawater enters the pool after filtration.
2. There are two ways to clear the pond: one is the dry water clearing pool, that is, the pool water is drained and exposed to the sun for 3 days to 5 days. The purpose of clearing the pool can be achieved. If it is deemed necessary, it can be reused. Qingchi liquid, some or all of the pool bottom and pool wall; the other is with a water clearing pool, which is sterilized together with the pool water, according to the amount of water to add drugs to kill the enemy, the pool of water is not soaked in the pool wall , with Qingchi liquid spill disinfection. The commonly used Qingchi drugs are the following:
(1) The available chlorine content of bleaching powder bleach is 25% to 30%, and the storage time is too long to be effective, so the available chlorine content must be determined before use. The amount of bleaching powder used in Qingchi is 60g/m3. When it is used, a small amount of water is added to make it into a paste, and then diluted with water. Bleaching ponds kill fish, crustaceans, algae and bacteria. After clearing the pond, its efficacy remained for 3 days to 5 days and then disappeared.
(2) Ammonia The amount of ammonia in agricultural ammonia is 15% to 17%, and the amount of ammonia in clear pond is 250ppm. Sprinkle after dilution. Ammonia clearing can kill fish, crustaceans and other animals. 2 days to 3 days after the clear pool efficacy disappeared.
(3) The amount of pentachlorophenol sodium in the clearing pool of sodium pentachlorophenol is 2 ppm to 4 ppm. After the water is dissolved, the sodium pentachlorophenol is uniformly sprayed and can kill fish, crustaceans, snails, and aquatic plants. The efficacy disappeared after a few hours.
3. After the irrigation effect disappears, it can be poured into the pool. The seawater that is poured into the pool must be filtered through a 250-mesh or 300-mesh tether net to remove predators. The pond should not be flooded too much. The first water intake is about 20 cm to 30 cm, and gradually increases.
4. Fertilization After cultivation of monocytic algae, the monocytic algae bait is fertilized and fertilized. The use of a mixture of organic and inorganic fertilizers allows the rotifer culture ponds to maintain their fertility for a long period of time to supply the nutrient requirements for algal blooms. There are many kinds of organic fertilizers, but the effect of fermenting chicken manure is ideal. Chicken manure must be fermented to avoid fresh chicken manure. In recent years, with the development of factory-based chicken farming, some units have selected chicken wastes and dried them at high temperatures to produce fish feeds mainly containing chicken excrement. If this kind of chicken excrement can be used, the effect will be better. Generally, 100 kg to 150 kg of fermented chicken manure is used as basal fertilizer per acre pond. If it is chicken manure fermentation feed, the amount of fertilizer can be reduced by 30%. When fertilizing, first spread 50% of the chicken manure evenly into the pool, and the remaining 50% will be piled around the pool, relying on the rainwater to make the fertilizer slowly flow into the pool or be used as a top-dressing fertilizer in the future. After application of basal fertilizer, 2 kg of urea and 0.5 kg of superphosphate are applied per acre.
During the clearing process, in addition to killing the enemy organisms of the rotifer, the rotifer's bait, unicellular algae, was also killed. Fertilization culture of single-cell algae needs to have algae species, and conditional ones can be inoculated with artificially-cultivated fine algae (such as Chlorella vulgaris, Platymonas, etc.) into the pool. However, due to the large area of ​​the earthen pond, a large number of algae species is needed, which is generally difficult to solve. Therefore, the rotifers in the earthen ponds often utilize various algae brought in when natural seawater is incorporated as cultivation species. Therefore, it is the culture pool with a water clearing pond that also needs to incorporate (or pump water) fresh seawater in some sea areas to solve the problem of cultivated algae species. Fertilizing and culturing single-cell bait can generally be propagated by algae from 4 days to 7 days. When the amount of algae is too large and the transparency of the pool water is less than 20 cm, 5 cm to 10 cm of water may be added every other day. When the pool water level rises to 50 cm, the rotifer species can be accessed. During the cultivation process, according to the growth of algae, the fertilizer is chased once every 5 days to 7 days in the same amount.
5. The vaccinated rotifers inoculum, generally 0.5 / ml ~ 1 / ml is more appropriate. It is possible to inoculate rotifers that have been continuously expanded with various kinds of rotifers or in culturing ponds where rotifers have reached their peak, and pooled rotifers.
6. Maintain the amount of algae bait. In the appropriate range, the rotifers are cultured in earthen ponds and are generally not baited. The rotifers mainly ingest diets of fertilized algae. Since there is a certain limit in the proliferation of cultured algae bait, the density of rotifers cannot be too high, otherwise cultured algae baits will be eaten at once, resulting in a large number of deaths of rotifers due to lack of bait. In order to balance the relationship between the two, the control rotifer density is generally between 5/ml and 20/ml, which will exceed the part of the harvest every day. On the other hand, through the application and top dressing, the proliferation of algae is maintained to supplement the rotifers. Consumption, so that the proliferation of algae and rotifer consumption of the basic balance, culture can be carried out normally.
7. Harvested rotifers can be trawled with 200 mesh screens and dragged along the edge of the pool; a float can also be placed on the surface of the tank and a cage made of 200 mesh screens can be installed on it. Using a small water pump, the pool water is pumped into the cage for filtration; the light-attracting characteristics of the rotifer-tailed rotifer can also be used to make the rotifers accumulate in a large amount of light, where the rotifers are concentrated in a brownish red color. Buckets are taken directly.
VI. Harvesting and storage of dormant eggs of rotifers The dormant eggs produced by bisexual reproduction of the rotifer Brachionus are easy to transport and store. People are accustomed to storing and storing rotifers in the form of dormant eggs. When needed, hatching can be performed to obtain rotifer species. At present, methods of inducing the formation of dormant eggs during the production of hermaphrodites are performed in combination with high population density and hunger stimulation. That is to say, the rotifers are first cultivated by conventional methods and are not harvested. When the number of rotifers reaches a peak, feeds are suddenly stopped and the aeration is stopped. The feed in the pool will soon be depleted, ie, sexual reproduction will occur. A lot of dormant eggs. Secondly, salinity or temperature can also be changed to promote rotifer production of resting eggs. The rotifers cultured under low temperature conditions are placed in a culture solution heated to 29° C. to 30° C., and are repeatedly operated once every two days. Through temperature stimulation, rotifers can artificially produce a large number of resting eggs.
After the rotifer has produced dormant eggs, the bottom sediments can be inspected every two days for microscopic examination, and the number of dormant eggs is large, and when they do not continue to increase, they can be harvested. First, the upper pool water is sucked out by siphoning, until the water depth of about 10 cm is left, then the sedimentation of the pool bottom is agitated, and discharged together with the pool water, filtered through a sieve over 300 meshes, and then washed repeatedly with clean seawater as much as possible. Remove the algal residue. The mixture of resting eggs and some of the algal residue was slightly dried and then bottled with a wax seal. It may not be dry, even a little concentrated bottled water, stamped.
Bottled and encapsulated rotifer dormant eggs are stored in a refrigerator below 5°C and can be stored for 1 to 2 years. Some dormant eggs are still capable of incubating for more than 8 years, indicating that dormant eggs can tolerate harsh environments. The time is quite long. The dormant eggs can also be left unsuctioned and kept in the original culture vessel or original pool. The original pool water cannot be drained or replaced with new water. If it is necessary to re-cultivate, remove the original pool water (attention to keep the bottom of the dormant eggs), exchange fresh seawater, and add a small amount of algae, the dormant eggs in the pool can be hatched, thus obtaining a large number of species of rotifers. However, the original pool to save dormant eggs, because of disease, the harm of predators, the survival rate is not high.

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