First, the collection and transport of broodstock American redfish broodstock in the United States, the main use of natural growth of fish in the sea area, in China mainly used ponds or cages of fish cultured, fishing mainly fishing and fishing nets. The broodstock must have a certain amount of time to acclimate before it is shipped, so that it can adapt to the life in the barrel. Short-distance transportation (within 5 hours) can be carried out by inflation. Ice must be added for long-distance transportation so that the water temperature can be maintained at about 21°C. Antibiotics can be added to the body of water to reduce the risk of bacterial infection.
Second, hormone-induced egg extrusion can be performed in a small, inexpensive tank, which can be synchronized with the spawning season.
1. Estimation of broodstock maturity During the spawning season (mid-August-mid-October), most of the broodstock caught can use hormones to induce ovulation, but examination of gonad development is required before hormone injection. For males, pressure can be applied on both sides of the fish and in the abdomen to extrude semen to check for sperm production. For females, one 1-2mm diameter glass tube can be inserted into the fallopian tube to obtain tissue samples in the ovary. The microscopic examination shows that the mature eggs are grayish yellow and the egg diameter is greater than 0.5mm.
2. Intramuscular injection of steroids can be performed when the ovum is injected into the hormone maturation stage. Human chorionic gonadotropin (HCG) of about 500-600 IU/kg fish weight induces ovulation within 24 to 30 hours at 25°C. In the final stage of maturity, the egg diameter will reach 1.0 mm, become transparent, and produce 1-2 oil balls. When ovulation occurs, the eggs will be squeezed out by squeezing out in the abdominal cavity. The insemination of eggs and sperm into the same container, while adding a certain volume of seawater (salinity 28, 32), agitated for 1 minute to count.
3. Post-fertilization procedures Transfer the mixture of fertilized eggs and seawater to a well-gassed 10 gallon aquarium for approximately 1-2 hours, then examine meiosis. If 70% or more of the eggs undergo meiosis, eggs can be placed directly into the incubator. If the fertilization rate is 30% to 70%, the inflating needs to be interrupted for a few minutes, live eggs will float on the water, and the dead eggs will sink to the bottom, and the dead eggs will be removed by siphoning.
Third, the hatching of fish eggs produced by the red buoyancy, spherical, diameter of about 0.9-1.0 mm, eggs transparent, most eggs with a golden yellow oil ball. Incubation usually takes place at 25°C within 4 hours and the vegetative organs are well developed after 48 hours of incubation. The optimal salinity for hatching is 28-35. The temperature should be kept above 22°C, the ammonia concentration should be lower than 0.5mg/L, and the dissolved oxygen should be higher than 3.0mg/L.
Fourth, the growth and development of larvae and feeding temperature is a relatively important environmental factor affecting growth. The ideal conditions for redfish eggs and larvae are temperature 25-30 °C, salinity 25-30. The larvae can grow 1 mm per day at a suitable temperature density and normal feeding conditions. Therefore, a juvenile from larvae develops to full scale juveniles in only a few weeks (3 weeks).
Feeding of larvae was carried out 3 days after hatching. Five rotifers/m1 were added at the beginning. Regardless of the fish density, they were fed 2-3 times a day until the larvae reached the 9-10th day and began to be fed Artemia nauplii. On the 1st and 2nd days, 1/m1, and then halve, can not make Artemia increase in the aquarium. After 15 days, the food has changed. At this time, some shrimp meal and commercial dry feed mixture can be added while feeding on Artemia. After about five days, Artemia can be stopped.
Fifth, the harvest of fry The red fish hardened, more vulnerable to injury than other species, large fry smaller fry adaptability. The fish was harvested after approximately 30 days of stocking. Collect some samples weekly with harvest boxes before harvesting. Collect good water quality and prevent low dissolved oxygen.
Sixth, the red-fish fry transport and adaptation There are two kinds of methods we commonly use. The first one is the canvas barrel transport, generally 1m2 barrels of seedlings for the 5000-10000 tail. The second type is the transport of plastic bags (oxygenation). This method is more commonly used in China and has the highest survival rate. The seawater is first loaded into the bag, and the fish is bagged and then filled with oxygen. After that, the bag is put into a foam plastic box. Generally, 300 to 400 fry of 2-3 cm per bag are loaded.
Second, hormone-induced egg extrusion can be performed in a small, inexpensive tank, which can be synchronized with the spawning season.
1. Estimation of broodstock maturity During the spawning season (mid-August-mid-October), most of the broodstock caught can use hormones to induce ovulation, but examination of gonad development is required before hormone injection. For males, pressure can be applied on both sides of the fish and in the abdomen to extrude semen to check for sperm production. For females, one 1-2mm diameter glass tube can be inserted into the fallopian tube to obtain tissue samples in the ovary. The microscopic examination shows that the mature eggs are grayish yellow and the egg diameter is greater than 0.5mm.
2. Intramuscular injection of steroids can be performed when the ovum is injected into the hormone maturation stage. Human chorionic gonadotropin (HCG) of about 500-600 IU/kg fish weight induces ovulation within 24 to 30 hours at 25°C. In the final stage of maturity, the egg diameter will reach 1.0 mm, become transparent, and produce 1-2 oil balls. When ovulation occurs, the eggs will be squeezed out by squeezing out in the abdominal cavity. The insemination of eggs and sperm into the same container, while adding a certain volume of seawater (salinity 28, 32), agitated for 1 minute to count.
3. Post-fertilization procedures Transfer the mixture of fertilized eggs and seawater to a well-gassed 10 gallon aquarium for approximately 1-2 hours, then examine meiosis. If 70% or more of the eggs undergo meiosis, eggs can be placed directly into the incubator. If the fertilization rate is 30% to 70%, the inflating needs to be interrupted for a few minutes, live eggs will float on the water, and the dead eggs will sink to the bottom, and the dead eggs will be removed by siphoning.
Third, the hatching of fish eggs produced by the red buoyancy, spherical, diameter of about 0.9-1.0 mm, eggs transparent, most eggs with a golden yellow oil ball. Incubation usually takes place at 25°C within 4 hours and the vegetative organs are well developed after 48 hours of incubation. The optimal salinity for hatching is 28-35. The temperature should be kept above 22°C, the ammonia concentration should be lower than 0.5mg/L, and the dissolved oxygen should be higher than 3.0mg/L.
Fourth, the growth and development of larvae and feeding temperature is a relatively important environmental factor affecting growth. The ideal conditions for redfish eggs and larvae are temperature 25-30 °C, salinity 25-30. The larvae can grow 1 mm per day at a suitable temperature density and normal feeding conditions. Therefore, a juvenile from larvae develops to full scale juveniles in only a few weeks (3 weeks).
Feeding of larvae was carried out 3 days after hatching. Five rotifers/m1 were added at the beginning. Regardless of the fish density, they were fed 2-3 times a day until the larvae reached the 9-10th day and began to be fed Artemia nauplii. On the 1st and 2nd days, 1/m1, and then halve, can not make Artemia increase in the aquarium. After 15 days, the food has changed. At this time, some shrimp meal and commercial dry feed mixture can be added while feeding on Artemia. After about five days, Artemia can be stopped.
Fifth, the harvest of fry The red fish hardened, more vulnerable to injury than other species, large fry smaller fry adaptability. The fish was harvested after approximately 30 days of stocking. Collect some samples weekly with harvest boxes before harvesting. Collect good water quality and prevent low dissolved oxygen.
Sixth, the red-fish fry transport and adaptation There are two kinds of methods we commonly use. The first one is the canvas barrel transport, generally 1m2 barrels of seedlings for the 5000-10000 tail. The second type is the transport of plastic bags (oxygenation). This method is more commonly used in China and has the highest survival rate. The seawater is first loaded into the bag, and the fish is bagged and then filled with oxygen. After that, the bag is put into a foam plastic box. Generally, 300 to 400 fry of 2-3 cm per bag are loaded.
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