Artificial propagation of loach and matters needing attention

Loach (Misgurnus anguillicaudatus) belongs to the family Loach. Misgurnus anguillicaudatus is known as "ginseng in the water". It is distributed all over southern China, which is not common in the north, but it is also distributed in different places. It can be harvested all year round, most in summer. After catching Loach, it can be used fresh or dried. Loach lives in the lake pond, and the body is small, only three or four inches long. It is round, short, with small scales under the skin, bluish black and covered with its own mucus, so it is slippery and cannot be grasped. It is a kind of fish with high nutritional value, which is different from other fish in terms of appearance, shape and living habits. it is a special kind of Loach. The body is slender and the front segment is slightly cylindrical. The rear side is flat, the abdomen is round, the head is small, the mouth is small, the lower position, horseshoe shape. The eye is small and there is no thorn in the eye. Must be 5 pairs. The scales are extremely small, round and buried under the skin. The back and sides of the body are grayish black, all have many small black spots, there are also many black spots on the head and fins, the spots on the dorsal fin and caudal fin membrane are arranged in a row, and there is an obvious black spot at the base of the caudal stalk. The other fins are gray. Loach is widely distributed in China, Japan, Korea, Russia and India along the coast of Asia. It is edible and used in medicine.

The artificial propagation of Misgurnus anguillicaudatus is very important for the cultivation of Loach, so farmers need to pay great attention. So how to carry out the artificial reproduction of Loach? What do you need to pay attention to?

Artificial propagation

Selection and cultivation of parent Loach: parent Loach comes from gully fishing. The bottom of the cultivation pond was covered with 20cm mud 7-10 days before use, the whole pool was disinfected with 150 million 200g quicklime per square meter, water injection 40~50cm, water injection was filtered with 40-mesh sieve silk to prevent pests from entering the pool, and an anti-escape net was set up with iron wire at the injection and discharge outlet. After the water temperature stabilized about 18 ℃ at the beginning of May, the Misgurnus anguillicaudatus with body length 15~20cm, body weight 30g, strong physique, disease-free and well-developed gonad was selected as the parent fish. The pectoral fin of the female was relatively short, and the front end of the fin was blunt and fan-shaped. When the fin was still, the fin was spread out on a plane, and the pectoral fin of the male was longer, and the tip of the leading edge winged upward. The captured parent Misgurnus anguillicaudatus was put into the culture pond according to the female-to-male ratio of 1 ∶ 2 for intensive cultivation, and the stocking density was 810 tails / m2. During the cultivation period, they were mainly fed with animal feed such as minced meat, minced viscera, fish meal and so on, accounting for 50.8% of the body weight of the parent Loach, supplemented by a small amount of plant feed such as rice bran, wheat bran and fresh water grass. Because Loach likes to look for food at night, feeding should be mainly in the evening. Wash and change the fresh water every 2 or 3 days, and each time the pool will be replaced with 1 beat, 4 cycles, and 3 pools.

Artificial induced labor

After the water temperature reached more than 20 ℃ on a sunny day around May 20, the mature gonadal parent Loach was selected from the culture pond. The belly of the female Loach was round, and there was colorless and transparent egg outflow from the abdomen under light pressure. The male Misgurnus anguillicaudatus was full of sperm and milky white semen was squeezed out of the abdomen. The dose of male Loach was halved by injection of 1 ml syringe and No. 4 needle. The needle was injected at the anterior and inferior sides of the dorsal fin. The needle showed an angle of 45 °to the parent Loach toward the head. The depth of injection was about 0.4cm, and the dose of male Loach was halved. In order to facilitate artificial insemination, the injected Misgurnus anguillicaudatus was put into two cages (1m × 1m × 0.5m, mesh 0.3~0.5cm) in the culture pond to observe estrus and spawn and carry out artificial insemination at the right time.

Artificial insemination

The female Misgurnus anguillicaudatus swims in front before spawning, the male Loach is urgent at the back, and the Loach is in estrus and moves the water surface. The parent Loach injected with oxytocin can be oestrus and spawn after 20 hours at a water temperature of about 20 ℃. When it is found that the female fish spawn, the parent fish are immediately fished out for dry fertilization. Dry the body surface water with a clean towel, squeeze the female Misgurnus anguillicaudatus eggs into porcelain bowls, porcelain pots or plastic pots, and immediately squeeze the male Loach. One female Misgurnus anguillicaudatus eggs with two male Loach semen, stirred by feathers for about 3 minutes, so that the semen and eggs are well mixed, fully fertilized, sprinkled on the fish nest, put into the incubation pond for still water hatching. The fish nest was disinfected with 20ppm potassium permanganate solution, and the washed willow roots and grass were made into small bundles, and the whole fertilization process was carried out without strong light.

Artificial incubation

Ten days before hatching, the incubator was thoroughly disinfected with quicklime, and when the effect disappeared, 30cm was injected, the fish nest full of eggs was tied on the bamboo rack, and the stone was used to fall into the water with 20-30 000 eggs per square meter. the top of the pool was covered with canvas to avoid bright light. The fry can be hatched in 3-4 days at a water temperature of about 20 ℃. The newly hatched Misgurnus anguillicaudatus seedlings are 2.5~3.6cm in body length and can not move freely. The ejector on the head is adsorbed on the fish nest and the pond wall. After 3 days, the fish fry are taken out and fed.

Loach seedling cultivation

The newly hatched loach seedlings can not move freely, attach their heads to fish nests or other objects, and take yolk as nutrition. The fry hatched in the pond are generally kept in the original pond, with a water depth of 20 cm to 30 cm and 500 to 1500 fry per square meter. if the density is too high, some of the fry should be taken out and cultured in another pond. Loach seedlings began to feed 3 days after hatching. At this time, you should feed boiled and ground egg yolk or fish meal suspension several times a day, and the feeding amount should be limited to eating within 1 hour. 2After 3 days, water fleas, rotifers, mashed silk earthworms or silkworm pupae were used instead. After about 10 days of cultivation, the fry can be transferred to the fry pond when the fry grows to 1 cm; the fish fry with low density can be cultivated in the retention pond, and then transferred to the fry pond after a month or so when the fry grows to about 3 cm. It can also be directly put into rice fields, ponds or pit ponds for adult fish breeding. The area of the fish fingerling pond should be 30-50 square meters. Before planting, the pond should be cleaned and disinfected, and basic fertilizer should be applied to cultivate bait organisms. The amount of seed is about 30 grams per square meter (800-1000 pieces). The fish species were fed with powdered formula feed twice a day in the second half of the pond, and the feeding amount was 3% or 5% of the fish seed weight. In summer, we should pay attention to the change of water quality at any time and change new water frequently. When the fish species grow to about 10 centimeters, it enters the stage of adult fish breeding.

Note:

During the incubation period, in order to prevent the deterioration of water quality and the death of embryonic development and hypoxia, new water should be added to the pond regularly to keep the water quality fresh and sufficient dissolved oxygen. At the same time, in order to prevent the occurrence of water mildew in eggs, 0.5ppm malachite green solution was regularly used to wash the nests full of eggs. When the larvae were all out of the membrane, the dead eggs were removed quickly to avoid the deterioration of water quality caused by egg corruption.

Meeting the opening feed of Loach seedlings is the key to improve its survival rate. The newly hatched Loach seedlings absorb the nutrition of egg yolk and mainly feed on rotifers and water fleas in water within two months after the disappearance of egg yolk. It is best to cultivate rotifers, water fleas and other zooplankton to feed Loach seedlings. Manure and chemical fertilizer are good fertilizers for raising Loach. It is necessary to continuously apply more fertilizer to the cultivation pond so that the seedlings of Loach have enough natural biological bait.

Misgurnus anguillicaudatus has the habits of partial feeding and foraging at night. If its special habit is changed, it should be artificially domesticated. Once a day in the evening, the feeding amount is from less to more, and the feeding time is gradually advanced. Until around 10:00 in the morning, 5 o'clock in the afternoon and artificial feed can be eaten.