High-yield culture techniques of freshwater grouper

Freshwater grouper is a tropical fish, native to Central America Nicaragua. It was introduced to Taiwan in 1988 and is a common freshwater culture species in southern Taiwan. In 1996, Guangdong and Jiangxi culture units were introduced from Taiwan. It has the characteristics of fast growth, hypoxia tolerance and strong disease resistance. Let's take a look at the high-yield culture techniques of freshwater grouper.

Life habits

Freshwater grouper can grow in fresh water or seawater with salinity below 10 ‰. The optimum temperature is between 25 and 30 ℃. The feeding decreases obviously when the water temperature drops to 20 ℃, and the body is out of balance when the water temperature drops to 15 ℃. Therefore, the area where the pool water drops below 15 ℃ during winter is not suitable for culture, and the water temperature for growth of freshwater grouper is above 19 ℃ during overwintering. The feeding habits are partial carnivorous fishes, and the carnivorous characteristics are strong in the fry stage, mainly zooplankton.

Reproductive habit

Freshwater grouper can lay eggs at the age of winter, and like tilapia, they dig many spawning nests at the bottom of the pond. Spawning usually takes place in the afternoon, and after spawning, the fertilized eggs are mainly guarded by females, and the males also cooperate with each other, but as the embryo develops, the guard behavior becomes weaker and weaker. The egg is oval, the egg color is yellowish dark green, opaque, sticky eggs, eggs scattered on the bottom of the pool, rarely overlap. The female fish weighing 140g laid about 3000 ~ 4000 eggs each time, and the larvae could be hatched after 48 hours when the fertilized eggs were fertilized at a water temperature of 26 ~ 29 ℃.

Seedling cultivation

1. Disinfection and stocking: the soil pond is the best in the freshwater grouper fry culture pond, and the water quality should be disinfected and fertilized with quicklime. The water should be tested before the fry is released, and the requirements for stocking in the same pond are the same. the density depends on the bait, the technical level of culture and the specification of cultivation.

2. Water quality management: the cultivation of freshwater grouper fry is easy to damage the water quality, and the water should be changed every 3 to 5 days, and the amount of water should be changed every time. Aquatic plants can be transplanted in the pond to purify the water quality and facilitate the concealment and eating of fish fry. When there are great differences in fry specifications, fish fry should be screened and cultured.

Bait feeding

1. Feeding of larvae: the feeding habits of freshwater grouper are carnivorous, and the larvae feed on zooplankton when they go down to the pond. with the growth of fry, the food intake increases, while the zooplankton in the pond decreases gradually. Zooplankton can be cultivated by topdressing and fed with soybean milk.

2. Domestication of larvae: freshwater grouper larvae can be domesticated when they reach more than 3 centimeters, first feed surimi on the table, add a small amount of formula feed to mix surimi after 2-3 days, and then gradually increase formula feed until all formula feed is used.

3. Feeding management: the daily feeding amount of freshwater grouper is about 20% of the body weight of fish, the protein content of formula feed is 35-40%, animal protein should be more than 25%, other plant protein raw materials can be added, and the feed coefficient can reach 0.8-1.2.

Adult fish culture

1, a small amount of mixed culture: a small amount of freshwater grouper can be mixed in the pond, about 2550 freshwater grouper per mu of water surface, the average body weight can reach more than 300 grams after half a year, and about 500 grams after one year.

2. Pond culture: freshwater grouper can be mixed-cultured tilapia, grass carp, crucian carp, etc., 150-200 fish per mu, 300 mixed-culture fish, the average body weight can reach about 200 grams after half a year, and more than 250 grams after one year.

Disease prevention and treatment

1. Rotten tail disease

[harm] the fin base of diseased fish is congested, the caudal fin, ventral fin and pectoral fin are the most serious, the body color fades, local redness and swelling and ulcers on the side of the body, and the mortality rate is as high as 90% in severe cases.

[prevention and treatment] wash with tetracycline or oxytetracycline for 4-10 minutes each time for 2-3 times, or sprinkle with furazolidone in the whole pool, once a day for 3 days.

2. Gill rot disease

[harm] the gills of diseased fish are reddish, the ends of the gills are congested, the local Gill tissue is necrotic and white, and in severe cases, the tissue decays and the cartilage is exposed.

[prevention] the whole pool was sprinkled with sodium dichloroisocyanurate, and the whole pool was sprinkled with 1520kg quicklime at a water depth of 1 meter per mu.

3. White spot disease

[harm] irregular leukoplakia appeared on the body surface of diseased fish, and in severe cases, leukoplakia became one piece, and the mucus on the body surface and Gill increased, swimming slowly, dyspnea, and often floated on the surface.

[prevention and treatment] washing diseased fish with fresh water for 2 minutes can kill pathogens, or wash diseased fish with copper sulfate for 2 hours for 2 hours for 3 days.

4. Vibrio disease

[harm] the body color of diseased fish faded, and local redness, swelling and ulcers on the body surface mostly occurred from April to November, especially from April to June, with a mortality rate of more than 90%.

[prevention and treatment] soak with furacilin and other antimicrobials for 3 minutes, or oral fish and shrimp Zhuangyuan mixed with 35% into the feed for 5-7 days.