CATDOLL : CATDOLL: How much does it cost to farm a thousand tilapia?

1. Pond farming

1. Pond conditions

The breeding site should be located in a place that is sheltered from the wind, sunny, with sufficient water, clean water, no pollution, quiet and convenient transportation. The pond area is 3 to 5 mu, the water depth is 1.5 to 2 meters, and the thickness of the pond bottom mud is 20 to 30 centimeters. Each pond is equipped with a 1.5-kilowatt impeller aerator.

2. Clean the pond and apply fertilizer

Before stocking fish, the pond should be cleaned and disinfected. Generally, in early to mid-April, 75 kg to 100 kg of quicklime is used to clean the pond per mu. After 7 days, water is added to a depth of 1 meter, and then 300 kg to 400 kg of decomposed manure is applied per mu. A small amount of green or red duckweed can be added.

3. Fish stocking

In spring every year, when the water temperature rises and stabilizes above 15℃, winter seedlings are stocked. Generally, 1,500 to 3,000 fingerlings are stocked per mu for main pond culture, and 40 to 70 silver carp and bighead carp are stocked at the same time to control water quality; when stocked with other fish, 200 to 500 fish can be stocked per mu.

4. Feeding

Tilapia can be fed 2 to 3 days after entering the aquaculture water surface. Tilapia has a wide range of diets. Under artificial breeding conditions, it can be fed with various feeds, such as wheat, early corn, cakes and dregs, which are all high-quality feeds. The protein content in the feed should be 32% to 35% at the beginning, and the daily feeding amount should be 3% to 5% of the total weight of the fish. When the individual size grows to about 200 grams, the feeding amount can be adjusted to 2% of the total weight of the fish, and the protein content in the feed should be 27% to 29%. When the individual reaches about 300 grams, tilapia enters the fastest growth period, and the daily feeding amount is maintained at 1% to 2% of the fish body weight, and the protein content in the feed is above 35%. Feed twice a day, at 8 to 9 am and 3 to 4 pm respectively.

5. In daily management, pay attention to patrolling the pond day and night.

(1) Measure water and air temperatures in the morning, noon, and evening every day, measure pH once a week, and measure transparency twice a week. Patrol the pond once in the early morning and once at night.

(2) After the fish are put into the pond, the water should be kept brown and transparent at 25 to 30 cm. Generally, fertilize once a week, and apply 150 to 200 kg of animal manure per mu each time. When the weather is clear and the water transparency is greater than 30 cm, the amount of fertilizer can be appropriately increased; when the water quality is too fertilized, fertilization should be reduced or stopped, and new water should be injected. In the hot season, the water should be changed once or twice a week, and 20% to 30% of the pond water should be changed each time.

(3) Adhere to healthy breeding, operate according to regulations, and prevent fish diseases. Before the seedlings are put into the pond, soak the fish body in 5% salt water or 0.1 mg potassium permanganate solution per liter for 10 to 15 minutes. Every 10 to 15 days, sprinkle 15 to 20 kg of quicklime water per mu throughout the pond to adjust the pH value of the pond water to slightly alkaline, and use biological agents to improve the microbial structure of the pond and improve the water quality. Turn on the aerator when the dissolved oxygen is low and the fish are slightly floating.

2. Rice field farming

Symbiosis of fish and rice can bring double harvest. When raising tilapia in rice fields, attention should be paid to scientific feeding.

1. Stocking Preparation

After the rice field engineering is completed, 2 weeks before stocking, 75 kg to 100 kg of quicklime water per mu is sprinkled on the fish ditch and field for disinfection. The next day, the ditch and the field bottom are raked once to fully mix the lime slurry with the silt. One week before stocking, fermented animal manure is applied to fertilize the water, with a dosage of 200 kg per mu to cultivate natural bait in the water.

2. Stocking time

Generally, the fish are released into the field about 5 days after the rice seedlings are transplanted, when the rice seedlings turn green. In some places, in order to increase the growth period of fish, fish are raised in the fish ditch in mid-May, and the fish are released into the field after the rice seedlings turn green. This is also an effective and good method.

3. Stocking method

Fish species should be selected that are strong, active, free of injuries and of uniform size. The stocking density should be reasonable. Generally, 200 to 300 tilapia with a size of 5 cm to 6 cm can be stocked per mu, along with 150 to 200 grass carp, carp, etc. The specific stocking amount can be flexibly controlled according to the conditions of the rice fields, water quality environment, irrigation and drainage conditions and management level.

4. Stocking operation

Fish should be disinfected before entering the pond, usually by soaking the fish in 3% to 5% salt water for 5 to 10 minutes. The time to release fish should be in the morning or evening on a sunny day, and avoid releasing fish on rainy days or at noon on sunny days.

5. Feeding and fertilizing

Tilapia is generally not fed in rice fields, and it grows entirely on natural feed. However, there is limited natural feed in rice fields, so feeding some feed can accelerate its growth and increase its yield. Feed twice a day, and the amount of feed should be controlled so that the fish can be eaten within 2 hours. There are no special requirements for basal fertilizer and farmyard manure in rice fields for fish farming. If urea, ammonium sulfate and other topdressing fertilizers are used, they should be applied in small amounts and multiple times, half a field at a time, and fertilizer should not be applied directly in the fish ditch.

3. Cage culture

Tilapia can be raised alone, as the main species, or in combination with other species in cages. Larger sizes are preferred, with tail weights of 10 to 50 grams. When the dissolved oxygen content is above 3 mg/L, the stocking density is 3 to 20 kg/m3.

4. Flowing water aquaculture

Tilapia is one of the main objects of current high-density aquaculture or "factory" aquaculture. The aquaculture pond should not be too large. Generally, 30 to 50 square meters is appropriate for fish cultivation. The dissolved oxygen content of the pond water should be maintained at more than 3 mg per liter. Intensive aquaculture requires feeding of a nutritionally comprehensive compound feed, and the protein content of the feed should be around 30%. Feed 5 to 6 times a day, and the feeding amount is 2.5% to 3% of the fish body weight.

Several key points in tilapia farming

Among the numerous tilapia seedlings, the most widely recognized ones are those bred by interspecific hybridization of tilapia. These seedlings have the advantages of hybridization, fast growth, large size, good cold resistance, and high male rate, and are generally recognized by farmers. The main commercial names are: Aoni, Aoza, Tilapia, Monosex Tilapia, etc. However, the quality of seedlings produced by various fish seed production units is quite different. Farmers should select a seedling with the fastest growth rate and the highest male rate from a large number of varieties through breeding and release.

Objectively, the monosex tilapia produced in my country, including the tilapia, has not reached a 100% male rate. In the breeding production, more or less inferior offspring are produced, which increases the stocking density, consumes a lot of feed, and does not meet the commercial specifications (its value is only about 20% of the normal product, called cat fish), which seriously affects the production efficiency of tilapia breeding. There are the following measures to deal with this problem:

1. Implement standard and coarse matching and graded breeding. Breeding producers should have enough second-level seedling standard and coarse ponds, with the first-level seedlings being standardized to about 20-50 grams and the second-level seedlings being standardized to about 200-400 grams, and then sorting male fish into ponds to grow into commercial fish. This can not only solve the problem of breeding too many "cat fish", but also avoid the problem of water waste in the early stage of breeding.

2. Regularly remove inferior offspring. Since tilapia fry have the characteristic of swimming in groups, every 2-3 days during the breeding season, use hand nets to collect and remove inferior fry at the edge of the pond.

3. Stock carnivorous fish appropriately. After the tilapia seedlings are stocked, some ferocious carnivorous fish such as largemouth catfish, river catfish, and spotted snakehead should be stocked appropriately (stocking specifications should be such that they cannot prey on the stocked tilapia) to prey on the offspring of tilapia. At present, if the farmers in Gaozhou City clean the ponds every crop, they generally raise 20 largemouth catfish per mu, and if they do not clean the ponds, they raise 20 spotted snakehead per mu.

4. Breed in batches and clean the pond after harvest. Except for small mountain ponds and reservoirs that cannot be drained and cleaned, general breeding ponds change the traditional catch-and-release method to breed in batches and clean the pond after harvest.

Due to insufficient funds and other reasons, many farmers consider the price of feed rather than its quality when choosing feed. Choosing cheap and inferior feed often not only fails to reduce feed costs, but also reduces production efficiency. The general requirement of compound feed for tilapia farming is that in addition to ensuring the crude protein content according to each growth stage, the key is to not contain toxic and harmful substances. Otherwise, it will affect the normal growth of fish at the least, and cause a large number of fish deaths at the worst, resulting in reduced production and reduced income. From the long-term practice of farmers in Gaozhou City, it is known that the main factors affecting the breeding of tilapia are feed mold and feed containing more rapeseed cakes with toxins. The vast majority of fish deaths in tilapia breeding ponds in Gaozhou City are caused by the above reasons. In particular, the most common occurrence of large-scale fish deaths is feeding feed containing about 20% rapeseed cake. Through the dissection and follow-up observation of these tilapia, as the feeding time increases, the liver and gallbladder of the fish continue to increase and the color becomes lighter. When they die, the liver has turned pink and yellow, the gallbladder has turned light yellow and transparent, and the liver and gallbladder have increased by 2-3 times. After the fish ponds with dead fish were switched to feed without rapeseed cake and feed with detoxification drugs, the dead fish phenomenon gradually disappeared. We believe that rapeseed cake is highly toxic, and it is not detoxified or the detoxification effect is poor in production, resulting in toxic accumulation after tilapia ingestion. When the detoxification capacity of the liver and gallbladder reaches its limit, it will lead to the death of the fish. For this reason, in the production of tilapia, care should be taken not to use moldy feed, and not to use or use less compound feed containing rapeseed cake.

In order to achieve high yield and high efficiency in tilapia farming, in addition to stocking high-quality fish species and feeding high-quality feed, it is also necessary to provide fish with a good growth environment so that they can grow normally and quickly. The key is to ensure the dissolved oxygen supply of the water body. Too large a stocking density will lead to insufficient dissolved oxygen supply in the water body, affecting the normal feeding and digestion and absorption of fish. Therefore, producers should set the stocking density according to the water capacity of the breeding pond (pond depth), water supply, whether it is equipped with an aerator and other conditions. The stocking amount is generally controlled at about 1-2 per cubic meter of water. The most suitable stocking amount should be determined by farmers in production practice. When the fish reaches the production specification period, the amount of feed that can consume about 2% of their body weight under normal weather conditions is the limit.

Summary of experience in prevention and control of tilapia diseases

In recent years, with the increase in export volume and the continuous improvement of people's quality of life, more and more attention has been paid to the quality and safety of aquatic products, and the demand for pollution-free aquatic products has been increasing. Therefore, it is imperative to carry out standardized and healthy tilapia farming. One of the focuses of standardized and healthy farming is disease prevention and control. The author has compiled the experience summarized from the tilapia farming practice in Huazhou in recent years for reference.

Fish disease prevention is mainly based on prevention, mainly by strictly controlling stocking density, adjusting aquaculture water quality, feeding nutritious and fresh feed, and regularly sampling fish for surface and anatomical examinations. Once a fish disease is found, aquatic professionals should be promptly consulted for diagnosis and treatment under the guidance of professionals. General measures are:

1. Thoroughly clean and disinfect the pond; 2. Strictly disinfect the fry and fingerlings before entering the pond; 3. After the fry and fingerlings are put into the pond, sprinkle the whole pond with 1g/m3 of 90% crystal trichlorfon. Sprinkle it with 1-2g/m3 of bleaching powder (28% effective chlorine) half a month later; 4. Keep the water rich, active, tender, refreshing, and slightly alkaline; 5. Dead fish should be fished out in time and buried in the soil after disinfection; 6. Utensils used in the sick fish pond should be soaked and disinfected, and the water in the sick fish pond must not be discharged without disinfection.

The use of fishery drugs must strictly comply with the relevant regulations of the State Council and the Ministry of Agriculture. The usage and dosage of external sprays and internal medicines should comply with the provisions of the aquatic products industry standard "Guidelines for the Use of Fishery Drugs for Pollution-Free Food (NY5071-2002)".

See the attached table for common fish disease prevention and control methods.