Nursery households should pay attention to “seven sees†when selecting broodstock in winter
Production practice has proved that choosing a good broodstock is the key to the success of artificial breeding fry. With the increase in the number of breeding, the broodstock declines year by year, so new and new ones should be replaced each year. When he chooses to stay, he should pay attention to "seven look." Look at the time. It is best to select broodstock before the Spring Festival (ie when lots of adult fish are harvested). It is best to fish into fish at a water temperature of 6°C to 10°C. At this time, the choice of broodstock due to reduced food intake of fish, activities are slow, tight scales, not easy to hurt. Second look at age. Self-supporting fish have a good idea. If you buy brooders from other places, you must understand the age of the broodstock. The cultured fish, the sexual maturity age is generally: carp 3 age -4 instar, carp, grass carp 4 age -5 instar, pupa, pupa, pupa more than 2 instar, black carp need more than 6 instar. Three look physique. To choose a healthy physique, complete squama rays, no disease, no traumatic fish as broodstock. Four look at weight. The larger the broodstock is, the more ovulation or storage is. General broodstock weight selection criteria are: squid 3 kg -4 kg, 8 kg squid, grass carp 7 kg, urn, pupa, pupa more than 1 kg. Fifth look at the blood relationship. If mating with the offspring of the offspring of the same broodstock, its offspring will exhibit undesirable traits, resulting in slow growth, disease, and reduced yield. Therefore, females and males used for breeding broodstock should come from different places, and the distance between the two places should be as far away as possible. Six to see the degree of gonadal development. When selecting broodstock, the development of the gonad (ovary or testis) reaches the third stage. Two methods can be used to observe, first from the outside, there are obvious ovary bulges on both sides of the abdomen; second, the autotrophic fish can choose several representative anatomy of the tail, you can see the ovary grow on both sides of the abdominal cavity, showing a grayish gray. In the winter, the ovaries are more than 2 cm wide and 15 cm long. Seven see male and female. According to the selected fish's pectoral fin, scales and other characteristics to identify male and female fish, male and female fish with appropriate proportions, generally 1:1, male fish can not be too much. In addition, some female fish older than 2 years old or male fish can be reserved in the adult fish pond in advance and reserved as broodstock, and male and female fish can be allocated accordingly.
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