Commercial Production
For the commercial production of Trichogaster Trichopterus, several steps must first be fol- lowed in order to synchronize spawning to have large numbers of fry of the same age for stocking.
Step 1. Sexing - Male gouramis can be distinguished by their longer dorsal fins which extend back to the caudal fin. In many cases they are also more brightly colored than the females. The females will have a shorter dorsal fin and should show some plumpness in the abdomen area. Broodstock should be selected based on size, color and apparent egg development in the females based on the plumpness of the female.
Step 2. Male and female broodstock are then placed in separate tanks for conditioning at a rate of one fish per ten liters (3 gal) with a ten percent water exchange per day to insure adequate water quality and provided with high quality feeds at least three times a day. Fish should be fed to satia- tion with caution taken to remove any uneaten feed from the tank. It is advisable to give a variety of feeds to the broodstock fish. This would include a complete commercial diet that contains at least 32% protein with a pellet or grind size no larger than about 1.0 mm. In addition to the commercial diets provide either a live or live frozen feed such as black worms, tubifex worms or blood worms as well as a paste made up primarily of beef heart and liver with a high percentage of vegetable matter such as peas and spinach (see appendix 2). Incorporating a high quality flake may also be helpful.
Step 3. After two weeks of conditioning the broodstock should be ready to spawn. Males are placed into the spawning tanks early in the morning so they acclimate and establish a territory. Ten gallon aquaria work well for Trichogaster sp. but use a larger or smaller container depending upon the size or genus offish you are spawning. The hatchery should be dimly lit with as little foot traffic as possible to avoid disturbing the pairs. In many cases males will begin construction of a bubble nest in the first two to three hours. With the Trichogaster sp. it is not necessary to add a floating substrate to facilitate construction of the bubble nest such as a floating ring, the bottom of a styrofoam cup or floating plants. In general, Anabantoids that are free spawners or mouth brooders do not require a floating substrate. Those that build foam nest and have floating eggs may not require a floating substrate but many times it is helpful in stimulating nest building behavior and spawning. Spawning containers should otherwise be bare and without any type of aeration as this will impede construction of the bubble nest. The females are then placed into the spawning con- tainer between 3:00 p.m. and 5:00 p.m. that same day.
Step 4. Spawning will take place over a period from one to four days. It is sometimes difficult to distinguish the eggs from the nest itself. The eggs are about the same size as the bubbles that make up the nest but have a darker golden or brownish tint to them. After spawning has taken
place, it is advisable to remove the female in order to avoid injury due to the males aggression. The male will then care for the nest and fry once they are hatched.
Step 5. The eggs will hatch in about 24 hours at 27oC (80oF) and remain in the nest another two to three days while the yolk sack is being absorbed. The fry are free swimming on about day four or five post spawn and are five to six millimeters in length. When the fry exhibit a distinct change in behavior swimming throughout the water column, they are ready to start actively feeding.
- 16 -
Step 6. The fry, in this stage of development are very delicate and should be moved with great care. Fry transfers should take place in the morning to avoid extreme differences in temperature and pH as well as avoiding photic shock. The fry tank water should be siphoned down using a large screened end on the siphon hose with a mesh size of 100 microns until there is 2-4 cm of water left in the tank. The entire container is then taken to the pond, being careful to keep sloshing to a mini- mum. Acclimation can then proceed normally adding small amounts of the growout tank water until the temperatures have equalized.
Step 7. Once the fry are ready to feed it is important to provide them with infusoria, rotifers or small Daphnia sp. Figure 8 provides a graphic representation of dietary transitions typically used in the rearing of larval gouramis. The change to freeswimming feeds is usually done by transferring the fry to a nursery pond or tank that has been prepared no more than ten days in advance. Nursery tank preparation is usually done by filling the tank with fresh clean water and adding a fertilizer with an N:P:K ratio of 1:3:0 usually in a liquid form with a concentration of 10-30-0. This fertilizer is applied at a rate of one milliliter per fifty liters of water. Additional or reduced fertilization may be needed for any particular site as long as you develop a plankton bloom dense enough to get a Secchi disk reading of 20-30 cm. Other fertilizers can be used at rates the farmer should determine for his particular site to achieve the desired Secchi disk reading. The larval tank can then be inoculated with Daphnia sp. or rotifers. Primary producers such as algae form the base of the aquatic food chain. In particular microalgae are of great importance to the commercial production of bivalves, crustaceans and finfish (Fulks and Main 1991). The rotifers Brachious calyciflorus and B. rubens have become the most commonly cultured rotifers in freshwater aquaculture (Hoff and Snell 1989). The Daphnia species are well adapted to considerable fluctuations of environmental conditions (Ivleva 1973). The proper species should be chosen to fit the environmental parameters of any particular farm site. For a reveiw of culture methods for microalgae, rotifers or Daphnia see Hoff and Snell 1989, lvleva 1973 and Fulks and Main 1991.
If the desired bloom is not achieved, the recently developed microencapsulated feeds and artificial plankton feeds can substitute for most if not all live feeds currently used on most commer- cial farms. Simply take the artificial feed add it to water and blend until all of the powder has been wetted. Spray this solution over the surface of the tank three to four times a day.
Step 8. Newly stocked fry should be fed to satiation 2-3 times a day with a commercial swim up diet and newly hatched Artemia from stocking until day 10 when the amount of artemia can be reduced at about ten percent a day until the fish are feeding exclusively on the commercial diet.
Commercial Production
For the commercial production of Trichogaster Trichopterus, several steps must first be fol- lowed in order to synchronize spawning to have large numbers of fry of the same age for stocking.
Step 1. Sexing - Male gouramis can be distinguished by their longer dorsal fins which extend back to the caudal fin. In many cases they are also more brightly colored than the females. The females will have a shorter dorsal fin and should show some plumpness in the abdomen area. Broodstock should be selected based on size, color and apparent egg development in the females based on the plumpness of the female.
Step 2. Male and female broodstock are then placed in separate tanks for conditioning at a rate of one fish per ten liters (3 gal) with a ten percent water exchange per day to insure adequate water quality and provided with high quality feeds at least three times a day. Fish should be fed to satia- tion with caution taken to remove any uneaten feed from the tank. It is advisable to give a variety of feeds to the broodstock fish. This would include a complete commercial diet that contains at least 32% protein with a pellet or grind size no larger than about 1.0 mm. In addition to the commercial diets provide either a live or live frozen feed such as black worms, tubifex worms or blood worms as well as a paste made up primarily of beef heart and liver with a high percentage of vegetable matter such as peas and spinach (see appendix 2). Incorporating a high quality flake may also be helpful.
Step 3. After two weeks of conditioning the broodstock should be ready to spawn. Males are placed into the spawning tanks early in the morning so they acclimate and establish a territory. Ten gallon aquaria work well for Trichogaster sp. but use a larger or smaller container depending upon the size or genus offish you are spawning. The hatchery should be dimly lit with as little foot traffic as possible to avoid disturbing the pairs. In many cases males will begin construction of a bubble nest in the first two to three hours. With the Trichogaster sp. it is not necessary to add a floating substrate to facilitate construction of the bubble nest such as a floating ring, the bottom of a styrofoam cup or floating plants. In general, Anabantoids that are free spawners or mouth brooders do not require a floating substrate. Those that build foam nest and have floating eggs may not require a floating substrate but many times it is helpful in stimulating nest building behavior and spawning. Spawning containers should otherwise be bare and without any type of aeration as this will impede construction of the bubble nest. The females are then placed into the spawning con- tainer between 3:00 p.m. and 5:00 p.m. that same day.
Step 4. Spawning will take place over a period from one to four days. It is sometimes difficult to distinguish the eggs from the nest itself. The eggs are about the same size as the bubbles that make up the nest but have a darker golden or brownish tint to them. After spawning has taken
place, it is advisable to remove the female in order to avoid injury due to the males aggression. The male will then care for the nest and fry once they are hatched.
Step 5. The eggs will hatch in about 24 hours at 27oC (80oF) and remain in the nest another two to three days while the yolk sack is being absorbed. The fry are free swimming on about day four or five post spawn and are five to six millimeters in length. When the fry exhibit a distinct change in behavior swimming throughout the water column, they are ready to start actively feeding.
- 16 -
Step 6. The fry, in this stage of development are very delicate and should be moved with great care. Fry transfers should take place in the morning to avoid extreme differences in temperature and pH as well as avoiding photic shock. The fry tank water should be siphoned down using a large screened end on the siphon hose with a mesh size of 100 microns until there is 2-4 cm of water left in the tank. The entire container is then taken to the pond, being careful to keep sloshing to a mini- mum. Acclimation can then proceed normally adding small amounts of the growout tank water until the temperatures have equalized.
Step 7. Once the fry are ready to feed it is important to provide them with infusoria, rotifers or small Daphnia sp. Figure 8 provides a graphic representation of dietary transitions typically used in the rearing of larval gouramis. The change to freeswimming feeds is usually done by transferring the fry to a nursery pond or tank that has been prepared no more than ten days in advance. Nursery tank preparation is usually done by filling the tank with fresh clean water and adding a fertilizer with an N:P:K ratio of 1:3:0 usually in a liquid form with a concentration of 10-30-0. This fertilizer is applied at a rate of one milliliter per fifty liters of water. Additional or reduced fertilization may be needed for any particular site as long as you develop a plankton bloom dense enough to get a Secchi disk reading of 20-30 cm. Other fertilizers can be used at rates the farmer should determine for his particular site to achieve the desired Secchi disk reading. The larval tank can then be inoculated with Daphnia sp. or rotifers. Primary producers such as algae form the base of the aquatic food chain. In particular microalgae are of great importance to the commercial production of bivalves, crustaceans and finfish (Fulks and Main 1991). The rotifers Brachious calyciflorus and B. rubens have become the most commonly cultured rotifers in freshwater aquaculture (Hoff and Snell 1989). The Daphnia species are well adapted to considerable fluctuations of environmental conditions (Ivleva 1973). The proper species should be chosen to fit the environmental parameters of any particular farm site. For a reveiw of culture methods for microalgae, rotifers or Daphnia see Hoff and Snell 1989, lvleva 1973 and Fulks and Main 1991.
If the desired bloom is not achieved, the recently developed microencapsulated feeds and artificial plankton feeds can substitute for most if not all live feeds currently used on most commer- cial farms. Simply take the artificial feed add it to water and blend until all of the powder has been wetted. Spray this solution over the surface of the tank three to four times a day.
Step 8. Newly stocked fry should be fed to satiation 2-3 times a day with a commercial swim up diet and newly hatched Artemia from stocking until day 10 when the amount of artemia can be reduced at about ten percent a day until the fish are feeding exclusively on the commercial diet.
การแปล กรุณารอสักครู่..
