Ayu culture requires clean water, no pollution, and low water temperature. Some aquaculture, such as mountain lakes, rivers, reservoirs, and foothill streams with lean water, low basic productivity, can be used for aquaculture. Under artificial conditions, young fragrant fish (5 to 6 cm) are reared for 5 to 7 months and generally weigh more than 100 grams. In recent years, the market price of sweetfish has been very high, and the production of aquaculture has gradually evolved. Among them, aquaculture has been the largest in Zhejiang and Fujian, and some places in Guangdong and Guangxi are also trying. Farming methods include the use of breeding grounds for cement ponds, aquaculture, and aquaculture. The aquaculture cycle is short, the market price is high, and the aroma fish consumption market in Japan is very large. As a kind of green and non-polluting food, the aquaculture fish is gradually formed in the domestic consumer market, which is quite promising for breeding.
The seedling technology described below is based on the scale of production of 1,000 to 1,500 seeds per cubic meter of water (5 to 6 cm in length).
(I) Major facilities
1. Nursery room should be east-west direction, glass fiber reinforced plastic tile roof nursery room, with black shading net to adjust the light intensity, control light intensity below 5000 lux. Nursery room windows should be wide and tall, which is conducive to ventilation and lighting.
2. The broodstock cultivation pool cement pool structure, round or rectangular, an area of ​​30 ~ 50 m 2, the pool depth of 1 ~ 1.5 m, drainage hole in the middle of the pool, the water level controlled by the valve, need to cultivate 2 to 3 pools.
3. Nursery pond cement pool structure, octagonal, round or rectangular, area 25-45 m 2, pool depth 1-1.5 meters.
4. The bait cultivation pond algae and rotifer culture ponds are rectangular or square, with an area of ​​10-30 m2 and a depth of 1 m. The area accounts for 20%-30% of the nursery ponds. At the same time equipped with Artemia hatching pond or hatching tank, hatching pool is a square cement pool, an area of ​​5 to 10 meters 2, the pool depth of 1.2 to 1.5 meters.
5. The water supply facility water supply system is seawater → sedimentation → filtration → disinfection → preheating → nursery ponds. For ground water or tap water for fresh water, if using tap water, pay attention to the content of bleaching powder in the water. When it exceeds 0.04 g/m3, the survival rate of larvae will be affected.
6. Inflatable facilities are equipped with inflatable equipment for broodstock breeding ponds, nursery ponds, and artemia hatching ponds. Two sets of Roots blowers RGA 5.5-3000 are used. The main and branch pipelines are used for air supply. The end of the branch pipe is equipped with No. 80 diffuser, and the seedling nursery puts 1 gas stone per 1-2m 2 and the brine shrimp hatch. The pool puts a gas stone every 0.5-1 m2. Small inflators can be used in the early and late nursery stages to save costs.
7. If the heating and power supply facilities are heated by boilers, a 0.5-ton boiler is generally installed in a 1000 m 2 nursery water body. If electric heating is used, generally plastic single-phase heaters and electric heating rods are used for heating. Self-provided generator or diesel engine driven air supply equipment.
(B) Breeding fish
1. The source of the broodstock was disease-free, healthy and healthy. The females had high ovulation, and the body weight was above 100 grams. Male fish weighing 50 grams or more were used as broodstock. Male and female segregation feeding, male to female ratio of 1: (1 ~ 1.5).
2. The broodstock cultivation density and number of cultivation density of 10 to 15 / m 2,100 m 3 breeding water bodies need to use 500 broodstock.
3. Feeding management of broodstock
(1) Feed Feed The feed is made in Japan with a bait or bait or domestic bacon with 10% to 20% pine needle powder and other cellulose to make a mass feed, and the feed amount is 2% to 3% of the fish's weight. %.
(2) Water quality control The temperature of the broodstock pool should be controlled within 27°C. The water exchange volume is generally 20%-50%, and the exchanged water is better with well water and stream water, and the dissolved oxygen is above 4 mg/L.
4. Diseases commonly used to prevent broodstock diseases include parasitic diseases, vibriosis, and enteritis. If it is found that the head of anchovy fish has mistletoe, use 0.2-0.5 g/m3 crystal trichlorfon to splash it; find that the algae in the pond are bred and the water quality is strong. Use 0.3 g/m3 copper sulfate and ferrous sulfate mixture. Spilled pool, occasionally use 0.4 g/m3 "Fish Ning" to prevent the occurrence of vibriosis and enteritis.
5. The broodstock is matured within 2 months before the egg-collecting period and can adopt the “short-day treatment method†to make the broodstock mature in advance. The method is: Covering the broodstock with a dark screen, shortening the sunshine time by 2 hours every 10 days, and the daily sunshine time by 8 hours. In order to feed the broodstock, the curtain was removed at 6 a.m. and re-covered at 2 p.m. Remove the cover, it should be slowly removed, if quickly removed, the broodstock will be frightened and hit the wall.
(III) Artificial oxytocin and hatching
1. The choice of spawning broodstock in early October, the female broodstock choose abdominal swelling, loose, reproductive hole reddish, digging to observe the egg diameter of 0.70 mm or more; males choose to have some semen in the abdomen as well.
2. The oxytocic acid injectable oxytocin is human chorionic gonadotropin (HCG) or luteinizing hormone-releasing hormone analogue (LBH-A) and injected intraperitoneally. The female injection dose is HCG10 international unit/g body weight or LRH-A 1 microgram/g body weight, and the male fish is halved. After 48 hours of injection, 80% of broodstock can be broiled.
3. Artificial insemination uses dry artificial insemination. Artificially squeeze the egg into the porcelain basin, then the male fish into the semen, male to female ratio of 1: (1 ~ 1.5), gently stir with feathers for 1 to 2 minutes, so that the eggs are fully mixed, and then fertilize the fertilized egg uniform The ground is attached to a clean brown sheet or dedicated ovipositor tiled on the water, with an egg density of 10 to 15 capsules/cm2. Avoid direct sunlight during artificial insemination.
4. Artificial incubation
(1) Incubation containers and environmental conditions can be controlled in cement tanks and cages. Incubation water temperature 15 ~ 22 °C, pH7.0-8.2, salinity 0 ~ 9 ‰, dissolved oxygen 5 mg / liter.
(2) Incubation method Use small bamboo rods to string eggs together and float in hatching tanks (or cages), or hang the brown eggs on ropes attached to the walls of the hatchery (or cage). Incubate well, change water or hatch water. Every 10 days, use 10 mg/elevated potassium manganate bath with egg brown tablets for 10 to 15 minutes to damage fish eggs or larvae with water-resistant mold.
(3) After escaping, the seawater of the ophthalmia was transferred to be fertilized and hatched. The film was gradually salted the day before the film was released, and was converted into seawater three days after the fish was released. The increase in seawater salinity was 6 to 8 per day.
(d) Seed cultivation
1. Seedling water and tools for disinfection and nursery water are precipitated, sand filtered seawater with a salinity of 10‰-30‰. Before use, nursery ponds should be disinfected with 100-200g/m3 bleach for one day, and then 50-100g/m3 potassium permanganate for half an hour. After disinfection, the pool should be cleaned, and the nursery tools should also be disinfected. .
2. The cultivation density is about 25,000 tails/meter 3, and when the larvae grow to 1.5 to 2.0 centimeters, they can be divided into conditions with a density of 0.5 to 10,000 tails/meter3.
3. Nursery management
(1) Water temperature and light control The incubation water temperature is controlled between 15°C and 25°C. In November, it is controlled above 14°C. The initial larval fish light control is between 2000 and 3000 lux, avoiding direct light. The larvae 50 to 120 days after hatching are most sensitive to light. When juveniles weigh more than 1 gram, they can develop normally under direct light.
(2) Sewage and water change The fry start to absorb the dirt 10 days after the opening of the fry, every 2 to 3 days to suck the dirt once, and after 30 days, the dirt will be sucked once a day. In the early stage of nursery, water is mainly added. The fish is changed about 10 days after the film is released. The water is changed 1-2 times a day and each time is 1/6 to 1/3. Change the water time 7:00, 18:00.
4. Feeding
(1) The rotifers are fed within 80 days after hatching, and are generally fed after the water is changed. The feed amount is 400 to 500/head per day, and 2 to 3 times daily. The rotifers were bred with chlorella for 24 hours prior to feeding.
(2) The egg yolks are fed within 50 days after hatching, and the amount of 300,000 tails fed with one egg yolk is fed, and the daily pitch is 2 to 4 times.
(3) Artemia nauplii began to feed 15 to 20 days after the opening of the nauplii, fed 3 times a day, and maintained 6-8 liters/liter of nauplii in the water. Before the feeding, it is necessary to strengthen the nutrition with marine fish oil for 24 hours.
(4) The leeches are fed 100 to 130 days after hatching once a day.
(5) Feeding begins after 7 to 14 days after hatching. The feeding amount was 3% to 6% of the fish's body weight and was fed 2 to 4 times a day.
5. The amount of aeration controls the initial stage of fry culture. The surface of the fish is in the form of microwaves. With the growth and development of the fry, the amount of aeration is adjusted in time to approximate boiling.
6. Drug control fish fry a day before the film with 0.25 ~ 0.5 g / m 3 of oxytetracycline spilled once, after the film with 0.25 ~ 0.5 g / m 3 oxytetracycline disease prevention.
7. When freshwater domesticated juveniles grow to an average length of 0.5 grams or more, they begin to acclimate. Gradually, the initial weight gradually decreased to 1.010 in the first week, and then gradually decreased to 1.002 in the next week.
8. Out of the tank as long as 4.5 to 6 cm can be out of the pool. One week before leaving the pond, fish fry nets must be trained. Stop food 12 hours before leaving the pool.
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