How to Raise Sea Bass? A Detailed Explanation of Breeding Methods and Technical Key Points
Sea bass is one of the common economic fish species. It has the characteristics of fast growth, wide adaptability, and strong disease resistance. It naturally feeds on small fish and shrimp, and artificial breeding offers high economic returns. So how do you raise sea bass?
1. How to Raise Sea Bass
1. Pre-breeding preparation
The area of a sea bass breeding pond should not be too large. If the pond is too small, the water body is narrow and dissolved oxygen is insufficient, making high yields difficult; if the pond is too large and too deep, it is not conducive to production operations.
A pond of 8-12 mu with a water depth of about 2 m is suitable, with sandy loam soil substrate, relatively little silt, a flat pond bottom slightly sloping toward the drainage outlet, a water depth of 1.54 m, a complete drainage and irrigation system, and an adequate, fresh, pollution-free water source with good water quality. The pond should preferably be equipped with inlet and outlet sluice gates leading respectively to intake and drainage rivers, and the aquaculture water should not be reused to avoid secondary pollution.
Ponds used for sea bass breeding must undergo drying, dredging, and sun exposure before fry can be stocked. Half a month before stocking, disinfection should be carried out once: apply 150 jin of quicklime per mu or use 20 mg/L bleaching powder with an appropriate amount of pond water for disinfection. If the pond has not been dried and sun-exposed, crushed tea seed cake should be soaked in water and splashed over the entire pond; if it has already been dried and sun-exposed, about 10-15 days before stocking, add water to about 10 cm, use 80-100 kg of quicklime per mu, and the next day add 5 kg of bleaching powder dissolved in water and splash it over the entire pond for pond clearing and disinfection, and thoroughly remove wild miscellaneous fish.
2. Stocking fry
The stocking period is from early December each year to March of the following year. Sea bass fry caught from sea areas with a body length of 1.5-2 cm must first be desalinated to a salinity of 4‰-7‰ before being placed in a temporary holding pond with a salinity of 1‰ for transitional holding. The general stocking density is about 8,000 tails per mu. Stocking is done at noon on a sunny day, when the water temperature and dissolved oxygen are relatively high, which can reduce discomfort to the fry. After being disinfected with water, the fry are placed into prepared mesh grids. Because high-density farming involves heavy feeding, and sea bass rarely search for leftover feed at the bottom of the pond, after removing the nets, a small number of crucian carp, tilapia, or bream (omnivorous) should be stocked per mu, along with a small number of bighead carp (filter-feeding), to reduce water pollution and increase breeding benefits.
Starting from the second day after entering the pond, feed live bait such as zooplankton and bloodworms, gradually mix fish paste and floating pellet compound feed with live bait, then gradually domesticate them to feed on minced fish paste and floating pellet feed. During the temporary holding period, splash 0.3 international units of strong chlorine or 15 international units of formalin for disinfection once a week. For 3 days before starting feeding, orally administer 0.5 g of furazolidone, 3 g of oxytetracycline, and 1 g of vitamin C per 50 kg of fish, mixed into feed and fed once daily.
3. Strengthen daily management
When sea bass fry are cultivated to a body length of about 10 cm, placing them in ponds for grow-out has a high survival rate. The stocking size should be as uniform as possible to prevent mutual predation. The stocking density should preferably be 1,000-1,500 tails per mu, along with 40 large-size bighead carp fingerlings, 20 silver carp fingerlings, and 200 Pengze crucian carp, to fully utilize the water body, regulate water quality, and increase yield.
September to October, when the temperature is suitable, is the rapid fattening stage for sea bass, and water quality regulation must not be neglected. After disinfection, the pond is filled with fresh water through a filter screen to a depth of about 80 cm, and some compound fertilizer is applied to cultivate plankton. Sea bass is a benthic fish that likes to live in clean water with relatively high dissolved oxygen (4-6 mg per liter, transparency of 30-40 cm). New water should be added flexibly and promptly according to water color and transparency. In the early stage, because the fish are small and the temperature is low, water quality is easier to control, and the cycles for adding and changing water can be longer. As the fish grow and the pond biomass increases, pond patrols should be done frequently, new water should be regularly added, and aerators should be reasonably used for oxygenation.
Feeding should achieve “fixed location, fixed time, fixed amount.” Generally, feed twice a day, at 6-7 in the morning and 6-7 in the evening. A feeding bridge should be set up in the pond, and each meal should normally be fed until about 80% full. In case of high temperatures or cooling, the feeding amount should be appropriately reduced. Each feeding should be accompanied by observation of the fish school's feeding and health conditions so that responsive measures can be taken promptly. Water quality should be kept fresh and dissolved oxygen sufficient. When stocking density is too high, large amounts of residual feed and excrement tend to remain at the bottom of the pond, and the decomposition concentration of harmful substances is high, consuming large amounts of oxygen in the water. As the fish grow, the frequency of turning on the aerators should be increased, and biological agents can also be appropriately applied to effectively degrade ammonia nitrogen and nitrite and maintain good water quality. At night, especially from 2-3 in the morning, the operation of the aerators should be inspected.
4. Scientifically prevent disease
Sea bass are prone to overeating and are susceptible to enteritis. During the day, observe changes in the sea bass's feeding to judge their health status. Sick fish have a distended abdomen and red and swollen anus, and a pale yellow mucus flows out when the abdomen is pressed. This is caused by feeding spoiled feed or overfeeding. The feeding amount should be appropriately controlled, which helps reduce costs, avoid water pollution, and reduce the occurrence of gastrointestinal diseases. During treatment, first reduce the feed, preferably skip one meal, and feed with broad-spectrum antibacterial drugs mixed into bait for 3-5 days to recover. At the same time, inspect whether any fish are swimming at the surface. Generally, before a large-scale outbreak, a small number of fish will swim at the surface. This is the best time for diagnosis and medication, and also a key period for prevention.
In autumn, hepatobiliary syndrome is prone to occur, mainly manifested as reduced feeding, gradually followed by fish swimming at the surface and unexplained deaths. The main cause is frequent drug application under high-density farming, with toxic and harmful substances in the water body chronically accumulating in the fish body, leading to organ dysfunction and tissue damage. Or it may be caused by long-term overfeeding, with the fish liver under long-term overload leading to metabolic disorder and metabolic disturbance. The water environment should be well regulated, feeding should be scientific, and regularly feeding Chinese herbal medicines for soothing the liver and promoting bile secretion mixed into feed has a certain preventive effect.
Parasitic diseases are prone to occur in autumn, so disinfection and deworming work should be done well. Generally, disinfect once every 15 days, with frequency depending on the fish's feeding conditions. Parasitic diseases mostly occur on the body surface and gill filaments of fish during the intermediate cultivation stage, manifested as emaciation, darkened body color, and mouth ulceration.
Generally, parasites can easily cause secondary bacterial infections, so disinfection is usually required after deworming. Water changes are often used to improve water quality for prevention. For treatment, 0.77-1 mg per liter of copper sulfate and ferrous sulfate mixture (5:2) can be evenly splashed over the entire pond, or 20-25 mg per liter of formalin can be splashed over the entire pond.