Selection of juvenile fish and management methods of adult fish in brocade carp culture

1. Selection of juvenile fish after hatching, the larvae are raised for 20 to 30 days, and when the fish grows to about 3 cm, they begin to select, eliminate the inferior and retain the good, and strengthen the growth rate, so as to achieve the purpose of protecting the characters. The selection of juvenile fish is the most important step to obtain high quality koi in the process of breeding. Generally, 3 or 4 selections are carried out within more than 3 months after hatching. The first selection was carried out within 20 to 30 days after hatching, and the length of the fry was about 3 cm. The main purpose is to select individuals with strong physique, lively swimming, straight spine, no deformity or defect of each fin and obvious characteristics of the variety. Other individuals are eliminated or bred separately for sale, but the growth rate and the time for the formation of markings are also different for different varieties, so the time for the appearance of variety characteristics is also sooner or later. For example, Zhaohe tricolor koi began to appear about 15 days after hatching, while gold koi appeared about 50 days after hatching. The second selection begins about 20 days after the first selection, and the selection criteria are whether the shape of each fin is beautiful, especially whether the pectoral fin, head shape is symmetrical, whether the eyes, kisses and tentacles are deformed, whether the color is bright and strong, whether the pattern is clear, whether the variety characteristics are obvious, and so on. The interval between the third selection and the second selection is about 20 days.

Selection criteria: the fin size ratio should be appropriate, the color should be bright, the white background should be pure, there should be no stains, the erythema should have a clear edge, the black spot should be uniform, and the markings should be balanced left and right, if there is a white part in the snout and tail handle, the variety characteristics are obvious and so on. The fourth selection is basically the same as the third. After the above three or four selections, in general, only 1000 to 3000 fish or less met the requirements of each fish. Koi is a large fish with edible value, and the fry selected and eliminated for many times can be raised as edible fish. Second, the feeding and management of adult fish the food intake of brocade carp is larger, and the stocking density is better. For large area cement pond culture, it is appropriate to breed 3-5 tails per square meter, properly mixed with grass, silver carp, bighead carp and so on. Koi is omnivorous fish, can be leftovers, leftovers, pericarp, etc., add about 10% of animal offal, longevity snail, maggot pupae, earthworms and other animal feed to make particles for feeding. The feed protein content should be about 35% and the fat content should be 5% to 8%. Should adhere to the "four fixed" feeding, specific feeding, according to the fish size, climate change and water quality of the appropriate amount of feeding, each feeding for 15 minutes is appropriate, the daily feed is 5%-6% of the body weight of the fish. It is generally fed at 6: 00 a.m. and 15:00-16:00 in summer and once at 13:00-14:00 in winter. Keep inspecting every day and pick up the residual bait in time. The water should be changed every 2-3 days in summer and every 4-5 days in spring and autumn. Keep the water quality fresh. In high temperature, cloudy and rainy weather, we should pay attention to increasing oxygen to prevent the occurrence of flooding pool. Koi can be moved indoors in winter, the indoor water temperature can be kept at 2: 10 ℃, and properly fed with digestible bait to ensure safe overwintering.