Silurus meridiondis chan is a large-scale carnivorous fish. It belongs to the scorpion-shaped head, commonly known as the bigmouth larvae. It is mainly distributed in the Yangtze, Jialing, and Tongjiang lakes. Since the 1980s, scholars in China have studied the reproductive biology, oxytocin production and insemination, juvenile fish development, and seedling cultivation of bigmouth bass. This article reports on the technical methods for the early breeding and early breeding of varieties in the Jiangjin Tropical Fish Breeding Farm using hot spring water.
1. Materials and Methods
1.1 Facilities Conditions
Two broodstock breeding ponds, each about 1 mu, with a water depth of 1.5 meters, the water source is supplied by the upstream hot spring water, and the winter and spring water temperature is >18°C, PH6.5-6.8; the incubator box is set; the seedling type temporary holding pool is 3, each 20 Square meters, water depth 50 cm; fry nursery pond 1, 100 square meters, water depth 1 meter. All kinds of equipment have a complete intake and drainage system.
1.2 Breeding and Selection of Broodstock
1.2.1 After the broodstock has been cultivated in spring, it begins to intensify the cultivation of large oysters. Every Other day, the pool water should be replaced within 15-20% 15-20%, and the water-filling capacity should be increased one month before the birth, increasing the stimulation of water production is the cultivation of broodstock in the inner pond. Necessary measures.
Feeds for broodstock cultivation include live feeds and compound feeds. Live feeds include animal feedstuffs such as loach, small trash fish, and animal viscera; broodstock feeds require crude protein content of about 40%, and substances that promote gonad development are also added.
1.4.2 Broodstock Selection In practice, the broodstock is often selected using the "see, compare, and touch" method. The abdomen of the female fish is swollen and soft and the outline of the ovary can be seen on the ventral surface. The abdomen of the male fish is clearly smaller than that of the female fish, the end of the gonopore is red, and there is semen outflow from the abdomen. The ratio of male to female of artificial insemination is 1:1.
1.3 Oxygen production and insemination
1.3.1 Preparations First, check the inlet and outlet pipes of the holding tanks and thoroughly clean the pool; second, ties the number of broodstocks in the holding pool; and third, build an incubator in the holding tank.
1.3.2 Drug Injection Females take two injections. At 10 am, females are injected with the first needle. The drug is luteinizing hormone-releasing hormone-5 (LRH-A5), 1.5 μg/kg, intrapleural injection. A second shot is given at 6:30 pm, females are injected at 15 micrograms/kg, males are halved, and placed in tie-boxes after injection. 1.3.3 Water temperature, water flow, and water quality Reproduction water is made of hot spring water. The water temperature is 20°C. The hardness of the water is high and weakly acidic. Immediately after the fish was placed in the tie box, it was stimulated by running water at a flow rate of 0.1 m/s, and the water stimulation was increased one hour before heat.
1.3.4 After two injections of artificial insemination, the estrus estrus reached its climax after 11-12 hours. Remove the female fish at this time, gently squeeze the abdomen by hand, so that the fish eggs into the dry basin, and then squeeze the male fish on the eggs (this process is best carried out in the dark), then pour the right amount of saline , Stir gently, and finally gradually add new water, repeated several times.
1.3.5 Incubation Spread the fertilized eggs evenly in the incubator. The water temperature is controlled at 20°C. The first day, the water is injected from the top into the new water. From the second day to the membrane, a still water hatch is used.
1.3.6 Larval rearing and fry cultivation At 20°C, the fish is hatched for 48 hours and the larvae are filmed for one day. Open the incubator and let it enter the holding tank. Start feeding a small amount of egg yolk or filtered rotifers and sticks. Corners, etc., began to feed leeches on the fourth day. After about 15 days of culture at about 20°C, the larvae grow to about 3 cm, and they are transferred to a seedling culture tank. At this stage, the phenomenon of mutual fry between fry is relatively serious, so in addition to the full amount of bait, the fish should be sieved every 8 to 10 days for grading.
2. Results
Throughout the entire period of early and evening, it was conducted twice. In 19 groups, 1.2 million fish eggs were hatched, 950,000 larvae were hatched, and the hatching rate was 79%. By the end of April, 70. .5 million fish species of more than 3 cm were bred and survived. The rate is 74%.
3. discuss
3.1 The experimental results show that the use of hot spring water for the early propagation of largemouth larvae is feasible, one month ahead of the conventional conditions, so that the growth period of largemouth larvae is prolonged by more than 15%.
3.2 The artificial breeding of largemouth larvae should pay attention to water temperature and water flow. Artificial breeding with hot spring water, the water temperature is basically constant, for water flow, because the egg viscosity is not strong, the water flow through the assembly to fill the egg membrane, so the flow rate should be less than 0.1 meters / second, and to prevent early release, Add 5-10 ppm potassium permanganate to strengthen the egg membrane.
3.3 Because of the small amount of semen of large-mouthed owls and the large amount of urine, urine should be collected first, and the ratio of male to female should be less than 1. In production, if the male is not enough, try to arouse the male parent several times (Li Deling, 1999).
3.4 Comparison of the effects of early spring propagation of hot spring water in the southern bigmouth puffer and the artificial breeding of large pond larvae in ordinary ponds. The rate of artificial insemination in ponds in the south can reach 92% (Huang et al., 1999). The artificial fertilization rate of hot spring water is lower, about 80%. Under conditions of water temperature of 19-24°C, the pond raises large mouth larvae. After 12 days of incubation, the survival rate was 87.7-93.1% (Chen Changqi et al., 1995), and in the hot spring water it took 15 days to reach the above specifications, and the survival rate was 75-80%.
3.5 It was determined that the hardness of the hot spring water was 5.8 meq/l, and calcium and magnesium ions were relatively high, but calcium and magnesium ions had effects on the hatching rate of large larvae, the survival rate of larvae and their growth. If water plants are planted upstream, calcium and magnesium can be removed from the water. In addition, accurate judgment of estrus estrus time, timely egg collection, insemination is also the key to improving the fertility rate. Because the effective fertilization time for mature eggs discharged into the ovary is 2 hours, the fertilization rate is reduced when the delay time is light, and the fertility is completely infertile.
1. Materials and Methods
1.1 Facilities Conditions
Two broodstock breeding ponds, each about 1 mu, with a water depth of 1.5 meters, the water source is supplied by the upstream hot spring water, and the winter and spring water temperature is >18°C, PH6.5-6.8; the incubator box is set; the seedling type temporary holding pool is 3, each 20 Square meters, water depth 50 cm; fry nursery pond 1, 100 square meters, water depth 1 meter. All kinds of equipment have a complete intake and drainage system.
1.2 Breeding and Selection of Broodstock
1.2.1 After the broodstock has been cultivated in spring, it begins to intensify the cultivation of large oysters. Every Other day, the pool water should be replaced within 15-20% 15-20%, and the water-filling capacity should be increased one month before the birth, increasing the stimulation of water production is the cultivation of broodstock in the inner pond. Necessary measures.
Feeds for broodstock cultivation include live feeds and compound feeds. Live feeds include animal feedstuffs such as loach, small trash fish, and animal viscera; broodstock feeds require crude protein content of about 40%, and substances that promote gonad development are also added.
1.4.2 Broodstock Selection In practice, the broodstock is often selected using the "see, compare, and touch" method. The abdomen of the female fish is swollen and soft and the outline of the ovary can be seen on the ventral surface. The abdomen of the male fish is clearly smaller than that of the female fish, the end of the gonopore is red, and there is semen outflow from the abdomen. The ratio of male to female of artificial insemination is 1:1.
1.3 Oxygen production and insemination
1.3.1 Preparations First, check the inlet and outlet pipes of the holding tanks and thoroughly clean the pool; second, ties the number of broodstocks in the holding pool; and third, build an incubator in the holding tank.
1.3.2 Drug Injection Females take two injections. At 10 am, females are injected with the first needle. The drug is luteinizing hormone-releasing hormone-5 (LRH-A5), 1.5 μg/kg, intrapleural injection. A second shot is given at 6:30 pm, females are injected at 15 micrograms/kg, males are halved, and placed in tie-boxes after injection. 1.3.3 Water temperature, water flow, and water quality Reproduction water is made of hot spring water. The water temperature is 20°C. The hardness of the water is high and weakly acidic. Immediately after the fish was placed in the tie box, it was stimulated by running water at a flow rate of 0.1 m/s, and the water stimulation was increased one hour before heat.
1.3.4 After two injections of artificial insemination, the estrus estrus reached its climax after 11-12 hours. Remove the female fish at this time, gently squeeze the abdomen by hand, so that the fish eggs into the dry basin, and then squeeze the male fish on the eggs (this process is best carried out in the dark), then pour the right amount of saline , Stir gently, and finally gradually add new water, repeated several times.
1.3.5 Incubation Spread the fertilized eggs evenly in the incubator. The water temperature is controlled at 20°C. The first day, the water is injected from the top into the new water. From the second day to the membrane, a still water hatch is used.
1.3.6 Larval rearing and fry cultivation At 20°C, the fish is hatched for 48 hours and the larvae are filmed for one day. Open the incubator and let it enter the holding tank. Start feeding a small amount of egg yolk or filtered rotifers and sticks. Corners, etc., began to feed leeches on the fourth day. After about 15 days of culture at about 20°C, the larvae grow to about 3 cm, and they are transferred to a seedling culture tank. At this stage, the phenomenon of mutual fry between fry is relatively serious, so in addition to the full amount of bait, the fish should be sieved every 8 to 10 days for grading.
2. Results
Throughout the entire period of early and evening, it was conducted twice. In 19 groups, 1.2 million fish eggs were hatched, 950,000 larvae were hatched, and the hatching rate was 79%. By the end of April, 70. .5 million fish species of more than 3 cm were bred and survived. The rate is 74%.
3. discuss
3.1 The experimental results show that the use of hot spring water for the early propagation of largemouth larvae is feasible, one month ahead of the conventional conditions, so that the growth period of largemouth larvae is prolonged by more than 15%.
3.2 The artificial breeding of largemouth larvae should pay attention to water temperature and water flow. Artificial breeding with hot spring water, the water temperature is basically constant, for water flow, because the egg viscosity is not strong, the water flow through the assembly to fill the egg membrane, so the flow rate should be less than 0.1 meters / second, and to prevent early release, Add 5-10 ppm potassium permanganate to strengthen the egg membrane.
3.3 Because of the small amount of semen of large-mouthed owls and the large amount of urine, urine should be collected first, and the ratio of male to female should be less than 1. In production, if the male is not enough, try to arouse the male parent several times (Li Deling, 1999).
3.4 Comparison of the effects of early spring propagation of hot spring water in the southern bigmouth puffer and the artificial breeding of large pond larvae in ordinary ponds. The rate of artificial insemination in ponds in the south can reach 92% (Huang et al., 1999). The artificial fertilization rate of hot spring water is lower, about 80%. Under conditions of water temperature of 19-24°C, the pond raises large mouth larvae. After 12 days of incubation, the survival rate was 87.7-93.1% (Chen Changqi et al., 1995), and in the hot spring water it took 15 days to reach the above specifications, and the survival rate was 75-80%.
3.5 It was determined that the hardness of the hot spring water was 5.8 meq/l, and calcium and magnesium ions were relatively high, but calcium and magnesium ions had effects on the hatching rate of large larvae, the survival rate of larvae and their growth. If water plants are planted upstream, calcium and magnesium can be removed from the water. In addition, accurate judgment of estrus estrus time, timely egg collection, insemination is also the key to improving the fertility rate. Because the effective fertilization time for mature eggs discharged into the ovary is 2 hours, the fertilization rate is reduced when the delay time is light, and the fertility is completely infertile.
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