Artificial culture technique of fine scale fish

The fine scale fish belongs to the genus Salmonidae, which has a small mouth. The posterior edge of the maxilla that extends beyond the eyes. One species is produced in China. Cold-water fish inhabit the low-temperature and clear water of mountain streams and spend the winter in deep pools or rivers of tributaries. The females mature at 4-6 years old, and the males mature prematurely than the females. Upward spawning and migration when thawing in early spring. The spawning ground is generally located in the rapids under the deep pool (the bottom is gravel and the water temperature is 8-12 ℃). Ovum sinking, 3.7-4.2 mm in diameter. Carnivorous fish also devour their eggs during the salmon breeding season. The meat is tender and high in fat, so it can be used as a new breeding object. Its natural resources have dried up.

The growth environment of fine scale fish

Fine scale fish is a residual species that moved from the north to the south during the ice age and belongs to cold-water Piedmont fishes. Living in mountain streams at an altitude of 9-2300 meters above sea level in the Qinling area, the water is fast, the water quality is clear, and the bottom is mostly large gravel, rich in dissolved oxygen, and the annual water temperature is no more than 20 ℃. Spend the winter in a deep pool or channel at the end of autumn. In the period of flood removal, it is rarely seen in the main stream of the plain.

Active feeding throughout the year. It mainly feeds on invertebrates and small fish, as well as frogs and small rodents. Extremely gluttonous, the food in its stomach can account for about 10% of its body weight, and it is better able to prey on fish of its own body size. The most appetizing time every day is in the morning and evening, and the rest of the time lurks on both sides of the stream with shady bottom. The appetite after spawning is particularly strong. Usually spend the winter in the deep water area of the river.

In the natural state, fine scale fish like to live in running water with low water temperature and fresh water quality, and spend the winter in deep pools or rivers of river tributaries in winter. Carnivorous fish mainly feed on invertebrates and small fish, as well as frogs and small rodents. The initial age of sexual maturity of fine scale fish is 3 Mel 5 years old. Sexually mature individuals spawn when the water temperature reaches 8 mi 12 ℃ from February to March each year, oocyte sedimentation and light yellow. Larvae like to lurk between sand and gravel, do not often flow, and usually feed on small fish, aquatic insects, small animals and plants living on water banks.

The economic value of fine scale fish culture

Fine scale fish has delicate meat and high fat content, so it can be used as a new culture object.

Fine scale fish is a national second-class protected aquatic wild animal, which has important academic research value in ichthyology and zoogeography. There were a large number of fine-scale fish before 1980, but due to human economic activities, overfishing and other reasons, fine-scale fish decreased greatly and were on the verge of extinction.

Qinling fine scale salmon has fast growth, delicate meat, no intermuscular thorns, delicious taste, has the function of preventing thrombosis and speeding up wound healing, also known as brain gold, with high nutritional value. The Song Dynasty is the tribute of the imperial court. Superior to rainbow trout produced in California, USA, rainbow trout was listed as one of the precious resources in Dingxi in 1981.

Culture techniques of fine scale fish

1. Larval fish culture. The culture container is a glass fiber reinforced plastic parallel trough (40 cm × 30 cm × 20 cm), which is cultured in running water. The influent flow rate is 1820 liters / min, and a 100 watt fluorescent lamp is set 60 cm above the water surface. The stocking density is 10,000 per trough. The total length of newly hatched fine scale fish larvae is 14-16 mm.

2. Juvenile fish cultivation. The juvenile fish pond is 10 meters long, 2 meters wide and 30 centimeters deep. Small scale fish larvae gradually float up and swim in the water after 2 / 3 of the yolk sac is absorbed. The stocking density of juvenile fish was 6000 / m2 in parallel trough and 3000 / m2 in juvenile pond. When the floating rate of juvenile fish reaches more than 50%, the opening feed should be fed with artificial formula feed. The artificial formula feed of juvenile fish with 45% crude egg content can be selected, but the fat content should be more than 12%. The particle size of feed is 0.3 mm and 0.5 mm.

3. Fish fingerling cultivation. Adopt the cultivation of the running pool, the running pool adopts the cement pool, the area of the single pool is 3090 square meters, the depth of the pool is 6080 centimeters, and the water depth is 50 centimeters. The pool is 1.2 to 2.5 meters wide. The slope of the bottom of the pool is 2 ∶ 1000mm 5 ∶ 1000. The water flow rate of the running pool is 100,300 liters per minute, keeping the water depth at 50 to 60 centimeters. The stocking density was adjusted according to the growth specification of fine scale fish. The stocking density of 5 grams of fish is generally 1000 fish / square meter; for fish of 10 grams, the stocking density is generally 800 fish / square meter; for fish of 20 grams, the stocking density is generally 600 fish / square meter; for fish of 30 grams, the stocking density is generally 500 fish / square meter.

4. Adult fish culture

① aquaculture: cement ponds are used. The cement pond is rectangular, with an area of 200 square meters, a depth of 100 cm and a water depth of 80 cm. The width of the pool is 6.67m, the length of the pool is 30m, and the slope ratio of the bottom is 12 ∶ 1000. The ponds are arranged in parallel. The source of water is groundwater with lower water temperature. The suitable water temperature for growth is 13-20 ℃, the optimum water temperature is 13-16 ℃, and the highest water temperature should not exceed 20 ℃. The pool water exchange rate should be more than 2 times per hour, and the flow rate should be kept at 0.02 ~ 0.16 m / s. Dissolved oxygen in water is more than 6 mg / L, and ammonia nitrogen should be controlled below 0.0075 mg / L. The stocking density is generally 150 fish / sq m for fingerlings of 20g / m2; for fingerling of 100g / m2, the stocking density is generally 150 ind / m2; for fingerling of 150g, the stocking density is generally 100 ind / m2; for fingerling of 200g, the stocking density is generally 75 ind / m2; for fingerling of 300g, the stocking density is generally 50 ind / m2.

② lake multiplication: choose the lake with dense aquatic plants (the coverage rate should be more than 90%), clear and transparent water body, no pollution, the highest water temperature in summer not more than 20 ℃, dissolved oxygen in water not less than 5 mg / L, the total amount of suspended matter in water not more than 15 mg / L, it is appropriate to release and multiply, and the water should also be rich in benthos, aquatic insects, small fish and shrimp and other bait organisms. Fine scale fish juvenile and 1-year-old fish species can be released. The size of juvenile fish should be 3 cm and 5 cm. The suitable stocking density is 10 ~ 30 tails / mu. The appropriate size of 1-year-old fish species is about 25 grams, and the stocking density is 5 fish / mu. Fine-scale fish have the habit of migrating to the depths of the river in late autumn and early winter, and fishing is usually carried out from late September to early October, otherwise the fine-scale fish will dive into the depths of the lake to survive the winter, which is very difficult to catch.