In recent years, the artificial seedlings and cultivating of the semi-slip tongue locust have developed rapidly in the northern regions (especially in Shandong Province), and their seedling raising techniques have also been studied in depth. The author briefly introduces the seedling raising techniques with the semi-slip tongue locust artificial seedling production as follows.
First, the fertilized egg was obtained
Now, fertilized eggs needed for nursery are generally obtained after breeding by domesticated wild broodstock. Wild broodstock under the conditions of artificial breeding through a certain degree of nutrition, water temperature and light control to achieve gonad maturation, and then through natural spawning or artificial insemination can obtain high-quality fertilized eggs.
Second, seed cultivation
1. Water conditions Water temperature 22 °C ~ 23 °C, pH above 7.9, dissolved oxygen above 4mg / L, light intensity of 200lx ~ 500lx about.
2. Feed organisms The feed organisms used for the large-scale breeding of semi-smooth tongue gills are mainly rotifers, Artemia nauplii, Artemia and compound feeds. The rotifer feeding time was 3 days to 20 days old, feeding 2 to 3 times a day, and the feeding amount was slightly better after the next feeding. The feeding tank was generally fed with the cultured water. The next 5 cells/mL gradually increased to 5 cells/mL to 10 cells/mL (L rotifers) as the fry grows. Artemia nauplii feeding time was 12 days to 50 days old, feeding twice a day, the feeding amount was maintained at 0.5/mL in the early stage, and gradually increased to 2/mL with the growth of fry. After Artemia fed for 45 days, it was fed twice a day and the growth of the fry was gradually increased. The fed amount was fed at about 10% of the fry weight. After feeding the compound feed for 4 cm to 5 cm in body length, it was fed once or twice a day. The fed amount was fed at 2% to 3% of the body weight of the fry.
3. Change the water during the cultivation of the seed, use a constant flow of water to change the water. As the fry grows, the water exchange rate is gradually increased, and it is maintained to 150% to 200% when it reaches the bottom.
4. In the process of cultivating seedlings at the bottom, in order to maintain the cleanliness of the water and sediment, the siphoning principle is used to suck out the dirt from the bottom of the pool. Check the bottom of the pool every day for the degree of contamination, and if there is more dirt, start the bottom. According to the specific conditions of the bottom of the pool, it can be sucked at the end of the first day every other day, and until the bottom is sucked every day.
5. Reasonable cultivating density From the newly hatched larvae to the large-sized seedlings, it is necessary to constantly adjust the cultivating density so as to reduce the pressure of the water tank, thereby increasing the survival rate and accelerating the growth rate. The density of the cloth pool is 5000/m3 to 10,000/m3, and it is maintained at 2000 to 3000/3000 m3.
6. Disease Prevention It is very important to effectively prevent the occurrence of diseases during the cultivation of seedlings. In general, disease prevention measures mainly include the following: First, disinfection of workers' bodies and tools; Second, reasonable cultivation density; Third, regular antibiotic antibiotic baths; Fourth, thorough prefeeding of food organisms. Cleaning; five is to keep the bottom of the pool clean and good water quality.
Third, the problem
During the cultivation of the semi-smooth tongue gills, a considerable number of fish fry appeared in the process of conversion of food organisms and compound feeds. The reason is unknown.
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