Breeding techniques of parent fish in silverfish culture
1. The source of parent fish.
Sexually mature individuals caught in the breeding season can be used for artificial reproduction; sexually mature individuals can be used for artificial reproduction; individuals that are not sexually mature shall not be used for artificial reproduction.
two。 The fishing of parent fish.
The fishing of large silverfish should be carried out during the peak spawning period. fishing can be started in the north of the Yellow River in early December and in the south of the Yellow River from mid-December. Fishing gear can be used Gill net (mesh 2a is 1.5-2.4 cm) or under-ice pull net. Parent fish should be caught in the spawning ground where spawning and reproduction are concentrated, and when taking fish on the Gill net, they should be picked gently from the head.
3. The cultivation of parent fish.
Individuals caught during the period of intensive fishing of large silverfish with strong physique and immature gonads may carry out parent fish storage, and shall comply with the following provisions:
(1) parent fish can be stored in cages or ponds.
(2) the specifications of parent fish storage cages can be 5 m × 5 m x 2 m, or 4 m x 4 m x 1.5 m, mesh 2a is 0.5 cm, and the area of parent fish culture pond can be 0.2-0.4 ha with a water depth of 1.5 m.
(3) the storage density of cages should not exceed 4000 m / m3 and that of ponds should not exceed 0.5kg / m3.
(4) during the storage time, a sufficient amount of small fish and shrimp should be put in for the consumption of parent fish, and the management of storage should be strengthened.
4. The choice of parent fish.
The sign of female maturity: a general healthy, large abdomen, small anal fin, triangular shape, egg flow in the abdomen after lifting the fish body, soft hand touch abdomen, egg outflow from the abdomen under light pressure, oval, bright and scattered. The sign of maturity of the male parent fish: the individual is smaller than the female parent fish, the abdomen is not dilated, the mature male chest is rose-red, the anal fin is wavy, the scales above the anal fin are large and adsorptive, and there is a crescent-shaped and milky testis on the left side of the body cavity above the cloaca.
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Loach on the Yellow River Plateau
Common name: Pike origin and delivery period: distributed in the trunk and tributaries of the upper reaches of the Yellow River. Introduction: a large fish of the family Loach. The head and body forequarters are flat, and the tail stalk is low and long. The mouth is large; the lips are narrow and smooth or shallowly wrinkled. It must be of medium length. The lower part of the unbranched dorsal fin hardens. The body is scaleless and the skin has short rod-shaped cortical prisms. Living in gravel sediment rapids, carnivorous. From April to May every year, when the river melts ice, it spawns against the current, which has a certain economic value.
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Technical measures of rice-fish rotation
To make preparations before raising fish, we must first raise and strengthen the ridges of the fields. Combined with the seedling or whole field of early rice, the ridge of the field should be heightened and widened as the basis of the later stage. After the harvest of early rice and the return of late rice, the ridge should be raised to more than 1.5 meters in time, and the width of the ridge should be about 1.2 meters. Secondly, it is necessary to do a good job in temporary recuperation ponds. The temporary pond is excavated in a corner of Honda, with an area of 15% to 20% of the size of rice fields. The depth of the temporary pond is about 1 meter. Finally, a drainage ditch was opened at a convenient end of the field to prevent the flood from rushing into the pond and causing the fish to follow the water.
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