Koi breeding natural reproduction

The selection of excellent broodstock is the key to good breeding of koi. To use natural reproduction, we must first choose the bred fish that meets the standards. In the north, the Koi, which was previously used as a breeding fish, was moved to an outdoor fish pond in mid-to-late March after crossing the winter. At this point, broodstock should be further selected to obtain excellent offspring.
(1) Selection of broodstock As a broodstock for reproduction, it is generally necessary to have the following: strong physique, bright and bright color, pure Lv lineage, clear varietal characteristics, clear and vivid margins, no imaginary edges, no ecchymosis, smooth and tidy scales, The swimming posture is stable and the fins are complete without defects.
(b) Identification methods of male and female fish Koi to mature age, there will be differences in the form of female and male fish. In general, the female body is short and thick, and the abdomen is enlarged. The closer to the childbirth, the more abdomen is enlarged and the head is slightly narrower and longer. The male body is relatively long and thin, with a wide and short section, and the forehead is slightly raised. . The pectoral fins of females are rounded; while the males are slightly pointed at the ends of the breasts, during the reproductive season, the distinction between females and males is more pronounced, and the first rays of the pectoral fins of the male and the lids of the pectoral fins appear Some white, rotten, small protrusions are called "chasing stars." Starchaser disappears after the reproductive season. The male genital hole is small and concave, and there is milky white semen flowing out by hand; female reproductive holes are slightly wider and flattened, slightly protruded outwards, and the eggs are gently pressed by the abdomen to escape; the koi carp breeds with the quantity of male and female broodstock. Whether it is appropriate or not has a great relationship with the fertility rate of the egg. In order to ensure sufficient numbers of spermatozoa and improve the fertilization rate of the egg, the ratio of female to male fertilization is 1:3 (1 female vocalist and 3 males form a group or 1:2 or 2:3 is better. The number of fish is small, and the ratio of male and female fish is 1:1. The gonads of 2- to 3-year-old female koi are just mature and their reproductive function is not strong, resulting in fewer pluck eggs and less rotten eggs. Prone to stunting, generally not selected as broodstock. Progeny breeding of broodstock. Progeny breeding of females is generally 4-10 years of age; and male fish must be in the 3-5 years of age, such broodstock, a strong physique, full gonads, The vigor of the egg and sperm is strong, and the fertilization rate and hatching rate are all higher. It is ideal for broodstock.
(c) Preparation of spawning ponds Cement ponds are used as spawning ponds. It is appropriate to use a pond with a pond area of ​​4 m x 4 m or a rectangular pool of 4 m x 5 m. The fish pond should not be too large and inconvenient to manage. If it is too small, it will affect the spawning activities of the broodstock. The water depth is 30-40 cm. The oxygen content is sufficient and the water quality is clean. The hydrogen ion concentration is 39.81-63.09 nmol/L (PH7.2-7.4). Micro-scale, low hardness water quality is better.
(D) Fish nest The fish nest is used to attach fish eggs. Prepare the fish nest before spawning. It is generally better to use wormfish, brown bark, willow roots (to be boiled many times over), etc., as a nest, and tie it into small bundles.
(v) Spawning in northern areas, from late April to mid-June, is the season for the spawning of koi, and when the water temperature rises to 16-18 degrees Celsius, the broodstock can be moved into the spawning pool and when the broodstock has a rapid chase phenomenon The fish nest can be rotated in the spawning pool. When the water temperature rises to 20 degrees Celsius, a large number of eggs can be laid. The time for spawning begins at about 4 o'clock in the morning until 10 o'clock in the morning or at noon. If the weather changes abruptly and the water temperature drops sharply, spawning will be interrupted. Generally, one oviposition of 30-40 cm in length is 200-400,000 eggs, and after about 1 month of spawning, it will produce the remaining eggs that were not produced before. Its eggs, like the eggs of goldfish, are also fertilized in vitro and are viscous eggs. The rotten size varies with the size and age of the mother. The mother is large and the egg diameter is large. On the contrary, the egg size is also small. The egg diameter is generally 2.1-2.6 mm. After the fertilized egg is absorbed, the egg diameter is lower than the egg size. Larger fertilized eggs. Fish nests that have been filled with eggs are removed from the spawning tank and immersed in a 5-7% salt solution for 5 minutes, or in a 1/10,000 part of malachite green for 10-15 minutes. Or immerse for 15 minutes in 3ppm methyl blue solution, disinfect, and then move into the hatching tank for incubation. The use of these drugs has certain effects on the prevention of the occurrence of watery mildew.
(6) Incubation The hatchery must be prepared first, with a cement pool of 3 m x 3 m in area and a water depth of 30 cm. The water temperature in the hatching pool should be the same as the water temperature in the spawning pool. When the water temperature is lower or higher than the water temperature in the spawning pool by 5 degrees Celsius, the hatching rate will be reduced, and an increase in the water temperature difference will cause the eggs to die. The length of the incubation period is related to the temperature of the water. When the hatching pool is turbid at 20 degrees Celsius, the larvae will hatch in about 4 days. The higher the water temperature, the shorter the required incubation time. On the contrary, the incubation time is longer, generally speaking, the water temperature. Fish can be bred for 4-5 days at about 18 degrees Celsius, fish can be fed for 3-4 days at 20-22 degrees Celsius, and fish can be fed for 3 days at 25 degrees Celsius. Hatched larvae do not feed and rely on the nutrients in the yolk sac to maintain the energy needed for survival. Adsorption on the fish's nest with attached organs on the fish body. When the nutrients in the yolk sac are absorbed, the larvae start to swim and feed. At this time, feeds can be started. Types of food and methods of feeding and feeding goldfish The larvae are the same way. In addition to the above methods, flow water incubators can also be used. This method should pay attention to the flow rate, and the flow of water can be larger. The fish nests that attach fish eggs are moved into hatch cages placed in running water to control the amount of running water. Higher, is conducive to the hatching of eggs, when the hatching hatched to reduce the flow rate, or placed in a static water cage to continue to develop. Otherwise, it will hurt the larvae, or because the larvae have a large amount of swimming, the pump strength is not good for development.

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