The Source and selection experience of Freshwater White Pomfret parent Fish in Culture

Colossoma brachypomum has strong reproductive ability, parent fish should be selected as large, fast growing, no disease injury, smooth body surface, clear color individuals as parent fish. Moreover, it is necessary to avoid fish with close relationship with green as parent fish, so as to avoid degeneration of offspring and affect growth.

(1) The source of parent fish Since the introduction of freshwater pomfret in China, the source of parent fish is mainly to select reserve parent fish from pond culture, cultivate them as mature parent fish, and carry out labor reproduction. In order to avoid the degeneration of offspring caused by inbreeding, offspring produced in more than two breeding sites can be selected as reserve parents.

(2) Parent fish selection

① Identification of male and female: When breeding parent fish and stimulating ovulation, it is necessary to master the appropriate proportion of male and female, so it is necessary to correctly identify the male and female of parent fish. Fish, like many vertebrates, are approaching or reaching sexual maturity when a second sex characteristic appears, especially in males, due to the physiological action of gonads secreting a sex hormone. The second sex character of Colossus brachypomus is not obvious all its life, so it is difficult to distinguish male from female. It is difficult to distinguish between males and females until the breeding season. Mature female fish abdomen visible obvious outline of the ovary, after the abdomen soft, elastic, genital pores and anus slightly red, obviously protruding from the outside. From the body color, compared with the male fish body color is darker, chest, pelvic fin, anal fin red is darker. The main characteristics of male fish at maturity are: red from chest to abdomen, darker and brighter than female fish, silver-gray body surface, slightly closed vaginal pores, flat abdomen, a small amount of semen flowing out of gently squeezed abdomen.

Age and weight: age and weight are positively correlated under normal circumstances, that is, the older the age, the greater the weight; vice versa. Due to the different ecological and nutritional conditions, the body weight of parent fish of the same age bred in different waters may vary greatly. The age of sexual maturity of freshwater pomfret is more than 3 years old, the weight of female fish is generally 2.5-4 kg, male fish is 2-3 kg, and the body length is more than 40 cm. The selected parent fish must be strong, smooth and unscarred fish as the parent fish for spawning.

Because of the large number of spawning, and within a year can lay eggs many times, so for general units, the number of parent fish need not be too much, as long as the parent fish is well cultivated, spawning, fertilization rate is high, 30-50 groups can be fully satisfied.