Barracuda breeding technology nine
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1. Water environment and improvement (1) Water temperature: The mortality of carp larvae is the lowest in water temperature from 20 to 27°C, and the best cultivation effect is obtained. When the water temperature was 22°C, the food intake was greater, and the food consumption at 20°C began to decrease. When the water temperature was 17°C, the food intake was stopped (Liao Yijiu). Nath thinks that the water temperature tolerated by the larvae is 18.9-25.3°C. Some larvae can survive at a low temperature of 15.9°C and a high temperature of 29.1°C. However, the survival rate of larvae is highest in the water temperature of 23-24.5°C. The temperature of cultivation of barracuda larvae can be lower than that of squid.
(2) Salinity: The suitable salinity of larvae is 32-35 ‰. Liao Yijiu believes that: Early larvae salinity should be stable, late in the period can begin to slowly add freshwater, larvae within 45 days from the original salinity 32.8 ‰ down to 4.15 ‰, more conducive to the growth of juvenile fish.
(3) Dissolved Oxygen: The amount of dissolved oxygen required for larval fish rearing is 5.4 mg/L or more. If the amount of dissolved oxygen is 4.8 mg/L, all larvae die after 96 hours. The highest survival rate within 96 h was dissolved oxygen 6.4-7.9 mg/L (Sylvester et al., 1975). According to observations by Tang Tiande et al. (1978), the barracuda hatchling fry was lively when the dissolved oxygen was above 3.53 mg/L, and was inactive when the dissolved oxygen fell below 2.69 mg/L, and the fry was 0.87 mg/L. All were in a coma and died after 4-5 hours.
(4) Illumination: Liao Yijiu (1974) observed that squid larvae are very sensitive to light, and 4-day-old larvae have phototaxis. To avoid direct light throughout the breeding process, the light intensity should be controlled at 600-14001x. Within 35 days after hatching, larvae usually eat food day and night, and 35 days later they are fed in the evening light. Some people think that: the fry within 5 days of hatching direct exposure to sunlight will cause death, so the indoor artificial light source is more favorable. Illumination also has a significant effect on food intake. Some people experimented that if the barracuda fish were properly lit at night, their feeding activities could be extended to about 12 hours at night. The measures to maintain a good water environment are mainly achieved through adding water. When the fry is in the beginning of the pool, the water level in the pool can only maintain about 40-60cm. When the water is shallow, the temperature of the pool water is easy to increase and the water quality becomes fat. However, by mid-care, due to daily feeding or fertilization, the water quality turns faster and the fish body grows rapidly. The original water space cannot meet the requirements for the growth and life of the fry, and it needs to be filled with fresh water once every few days to increase The oxygen content of the water body improves the water quality, expands the space for fish movement, and promotes the growth of fry. The fish seedlings are generally injected once every 5 to 7 days, each time injecting 20-30 cm, until the summer flower is discharged before the pond is added to a certain level. When water is injected, use a dense mesh to prevent the wild fish and eggs from entering the pool with water. At the same time, water should be prevented from flowing through the large mixing pool.
2. Topdressing and Feeding The current practice of seedling cultivation in the earthen ponds is based on fertilizing bait and pouring soya milk in the early stage. Later, soybean meal paste, peanut cake paste, corn batter, and artificial feed can be used to directly feed fry. After the fish have entered the pond, top dressing should be applied in time according to the color of the water and the amount of plankton in the pond. The fertilizer is usually applied once every 5 days or so. Each time, about 50kg of dry manure or manure is applied per acre, and every day, each mus: 1kg of soya bean milk (80 to 120 mesh sieves removes bean dregs) and 15 egg yolks. Dosage, spilled into the pool. Rotifers can also be supplemented and fed. About 3 days after entering the pond, Artemia nauplii can be added. When the fish fungus grows to 1.5 to 2 cm, and begins to feed on plant foods, the above-mentioned bait can be evenly sprinkled in shallow water near the pool. The daily feeding amount of young fish can be about 5-8% of body weight.
3. Patrol Pool is a very important task in day-to-day management. In the process of fry growing summer flowers, you must patrol the pool every day. In the early morning and early evening, observe the status of fish fry and the change of water color in order to determine the amount of fertilizer and feeding. If the fish floats every morning and does not release after sunrise, it needs to be filled with fresh water immediately to make up for the lack of oxygen in the water. At the same time, it also shows that the water quality is too fat and it is necessary to appropriately reduce or suspend the fertilization and feeding. In addition, attention should be paid to observing the occurrence of fish disease and whether or not the fish should be caught in order to take corresponding measures. At any time, dead seeds, weeds and dirt are removed from the water.
4. Pulling nets to work and going out of the barracuda seedlings are generally cultivated in the pond for about 25-30 days, and the body length can be as long as 2.5-3 cm. At this time, after the nets are trained, the ponds should be cultivated in time. The purpose of the net-grip exercise is to enhance the fish's physique and its resistance to the external environment, so as to reduce the casualties and improve the survival rate in the process of transportation and division. Because the netted fry is frightened, it increases the amount of exercise and makes the muscles strong. At the same time, it makes the fish accustomed to disturbing stimulation and intensive environment, reduces the secretion of mucus in the transport of fish, and excretes the feces, which is not easy to pollute the water and is easy to transport. . Pulling the net is usually two to three times, and each pull time is one day apart. Pull the net for the first time, put the fish together with the plastic gauze net or the linen net, put it back immediately; The second net pulls the fish into the cage after being dense for 2 hours and then the third net pulls the fish About 2 hours in the cage, you can count, out of stock. The net exercise should be conducted in the sunny morning (9-10h). If there is a floating head, it should be resumed after normal recovery. In case of severe weather such as heavy rain, it should be stopped whether it is being arrested or not. Before each pull, you need to stop feeding. In particular, the barracuda seedlings come out of the pond at the end of June, and the water temperature is relatively high. Therefore, the net operation must be meticulous, especially the first and second pull nets. Carelessly, juvenile fish scales are easily detached, resulting in injury and even death. The speed of advancement must be balanced and steady and slow when pulling the net. After the fish enters the cage, there must be a special person to watch it, keep pushing in the water or gently splash water at the end of the box to keep the inside and outside of the box open.
(5) Factory-scale nursery The factory-built nursery pond is a rectangular concrete pool located in the nursery room, and can also be brick-cemented. Single pool of water 15-30m, pool depth 1.5-1.7m. The bottom of the pool is flat and tilts toward the end of the drain. Nursery ponds should be provided with factory-based nursery equipment such as intake and drainage, aeration, and warming, as well as animal and plant feed cultivation facilities. Before the fry is released, the seedling pool must be strictly cleaned (with the method of clearing ponds with shrimps), sand-filtered or net-filtered seawater pools, and fertilized, inoculated, and propagated single-cell algae, followed by propagation of small zooplankton for feeding fry. The seedling density is about 50,000/m3, and the feeding period is mainly for feeding. The type of bait is in order: shellfish fertilized eggs and trochophore larvae, copepods nauplii and small rotifers - rotifers And copepods - Artemia nauplii - in food products (oil cake paste, bran bran and artificial feed, etc.). Can also be fed soy milk, egg yolk, yeast substitute feed. Should change the amount of water every day, continuous inflation, strict monitoring. After about half a month of training, the fry have begun to swim in groups and the predation ability has been greatly enhanced. The “dangerous period†of larvae has already passed, and the fish can be moved outside and continue to be cultivated.
Sixth, after the fish seedlings cultivate summer flowers, they need more food and more space for activities. If you remain in the original pool and have a high density, it will affect the growth of the fish. Such as direct stocking into large water bodies to develop food fish, because the summer flower body to escape the enemy invasion and feeding ability is still poor, it is easy to cause a lot of losses. Therefore, it is generally necessary to go through the rearing stage of the fingerlings, and continue to raise the summer flowers after the ponds to the winter of the current year or the spring of the following year, and develop fish species of about 10 cm or more in size, and then release various types of waters to develop food fishes. .
(1) Pre-stocking preparations The basic conditions for the fish breeding ponds are generally the same as the fry ponds. The area of ​​the pool can be larger, generally 2-5 acres more suitable, after the summer flower out of the fry cultivation pool can also be used for breeding fish species. The method and requirements for the clearing of the fingerling ponds are the same as those for the fish seedlings.
(2) Fish fingerlings, stockings, and fry fillets are used for raising fish species, which can be cultivated individually or with other fish species. The density of monoculture mainly depends on the specifications of the cultivated species, pond conditions, feeding conditions, and fertilization. The barracuda is generally single-cultivated, with 6000-8000 tails per acre, and it can be reared to a size of about 10-12cm at the end of the year. Carp stocking density can be slightly higher.
Polyculture can make use of the difference in feeding habits of different species of fish to fully utilize the pond's natural food organisms and increase the productivity of fish ponds. The common barracuda and barracuda are generally mixed with alfalfa or grass carp. When the alfalfa and barracuda are the main species, they can store oysters, barracudas, summer flowers 4000-6000 per mu, and grass carp 2000-3000; grasshoppers or grass carp. When it is dominant, 5000-6000 tails of grasshopper or grass carp can be placed per acre, and about 2000 tail fish and lobster fishes. For example, in the semi-intensive prawn pond, 500 bolls of summer fish can be released per acre, which can grow to about 100 g. As a winter fish species.
(C) Feeding Management The central task of feeding and management is to provide sufficient food to meet the needs of fish growth and development under the premise of ensuring water quality. The method of fertilizing and breeding feed organisms can be adopted to play the role of the basic bait of the pond, and rational feeding according to the principle of "four settings" (quantitative, quantitative, positioning, timing) feeding. Oil cakes, rice bran, bean dregs, distiller's grains, silkworm cocoons, and artificially-combined baits are the favorite foods for clams and barracudas. During the breeding process, appropriate amount of fresh water should be injected frequently. In the whole course of cultivation to winter fish species, at least 4 to 5 times of water should be added. Patroling, observing, preventing flight, and preventing disease are essential daily management tasks.
(4) After 4-8 months of feeding from summer fry seedlings in Tongtang (due to the fact that the climate varies greatly from place to place, the length of time for the growth of oysters and oysters is also different). When the weather turns cold, the water temperature drops to 13-14. Below °C, the fish's activity is weakened, and then the water temperature continues to drop, gradually stopping feeding, and should be reduced and stopped feeding in due course. After the winter, after 4 to 5 days of feeding, you can select sunny days to pull nets and ponds, can be counted according to size specifications, and then into the wintering pool for winter.
(V) Over-wintering of fingerlings Currently, there is a common difficulty in over-wintering in seawater in the production of barracuda in northern China, and the survival rate is low. It must be raised in the current year, and it must be collected in the same year. This is uneconomical in terms of economic value and food value. The barracudas in the northern harbor have an average body length of about 13cm, a body weight of only about 25g, and they are well raised, only 60-80g. If it is continued to grow in the second year after winter, the growth will be accelerated. Under the condition of not feeding bait, the body weight can be increased to 250g and the intensive intensive feeding can reach 500-600g. In the second year of life, the limpets have a strong life force, few diseases, high survival rate, and a lot of meat and fragrant oils. Therefore, it is one of the key technical measures to increase the per unit area yield of squid and barracuda through the wintering of barracuda and barracuda.
The cold hardiness of barnyardgrass and barracuda was poor. The lethal temperature of barracuda was -0.7°C and the total lethal temperature was 1.2°C. The freezing point of a water body with a specific gravity of 1.008 (corresponding to a salinity of 10 to 11 ‰) is -0.7°C, which is the critical temperature for maintaining the survival of the fish. The hardiness of squid is even worse. Maintaining a suitable wintering temperature is the key to ensuring the survival rate during the wintering period. The specific measures for overwintering barracuda in northern China are:
1. Overwintering ponds should be constructed in relatively overwhelming terrain, with less silt and weeds, and hard-bottomed, non-leaky ponds for wintering ponds. It is best to shelter from the wind, injection, and drainage. Pool water depth should be maintained at 2m or more. According to the experience of the Hebei Qianxu farming team: Deep trenches are excavated in the breeding ponds to maintain a high water temperature in the trenches. The team used a 2m wide, 1.5m deep, 20m long ditch for good overwintering effect.
2. The overwintering species that are stocked and raised by the fingerlings should be robust and the fish body must be full so that the fish can have sufficient ability to maintain life during the winter. Care should be taken when stocking to prevent fish injuries.
The sooner or later time for stocking wintering fish species should generally be based on the optimum temperature of barracuda and barracuda. When the temperature of the fish is above 10°C, the barracuda should be pooled for winter at 8°C. Overwintering fish species should not be stocked too densely, and over dense and susceptible to lack of oxygen can cause large numbers of fish species to die. Taking lobster fish as an example, 15 fish species of 25 g weight can be placed per cubic meter of water. The pool that changes the water once a month or so can store about 30 fish per cubic meter of water.