Experience and Technical Key Points for Pond Farming of Bass

1. Pond clearing and water cultivation

For ponds used to farm bass, it is best if conditions allow to dry the pond, remove silt and expose it to sunlight, especially for old ponds that have been farmed for many years. Disinfect once half a month before releasing fry, applying 50 kg of quicklime per mu or using 20 PPM bleaching powder with an appropriate amount of pond water for disinfection. If the pond has not been dried and exposed to sunlight, 30 kg of tea seed cake per mu should also be crushed, soaked in water and splashed over the whole pond to thoroughly remove leftover ferocious miscellaneous fish. After disinfection, filter fresh water into the pond through a filter net, and apply 3 kg of compound fertilizer per mu to cultivate plankton. When the water is slightly green or slightly brown, fry can be stocked.

2. Stocking density

After intermediate rearing, the fingerlings have reached 10 cm. Stocking 2500 per mu is preferable, and over a 300-day farming period the yield per mu can reach 1200—1500 kg. If stocking is too dense, the pond is prone to aging and fish diseases, making sustainable production difficult. Because high-density farming involves heavy feeding, and bass rarely seek leftover bait at the pond bottom, 100 crucian carp and 30 silver carp and bighead carp per mu should be stocked to reduce water pollution and increase farming benefits.

3. Feeding. Bass are gluttonous

Properly controlling the feeding amount helps reduce costs, lower the occurrence of gastrointestinal diseases and reduce water pollution. Feeding should be done at fixed times, fixed locations and fixed amounts. Generally feed twice a day, at 7—9 am and 4—6 pm, with the daily feeding amount about 5% of the fish body weight. Persist in the habit of taming them to feed. Build a feeding bridge in the pond, and each time you feed, strike the feeding bridge or splash the pond water loudly to call the school of fish to come and compete for food, which helps observe the fish school's feeding and health status and makes it convenient to take responsive measures. Bass compete for suspended feed in the water, and once it sinks they no longer eat it, so when feeding small miscellaneous fish, feed patiently and slowly, while pelleted feed should be floating feed.

4. Water quality management

High-yield bass farming is high-density farming, and keeping the water fresh and dissolved oxygen sufficient is very important. The main methods are: change water frequently, especially in the middle and later stages, with the daily water exchange reaching more than 30%; increase aeration frequently. During the fry stage, aerators can be turned on appropriately. As the fish grow, the frequency of turning on aerators increases, especially in high-temperature weather and the later stage of farming. At night, some aerators can be turned on, while during the day all aerators should be turned on, keeping the dissolved oxygen in the pond water above 5 mg/L; apply biological preparations. High-density farming brings large amounts of leftover bait and excrement at the pond bottom, and the decomposition concentration of harmful substances is high, consuming large amounts of oxygen in the water, especially serious in high-temperature weather. This is an important cause of fish diseases. Properly applying biological preparations allows beneficial bacterial flora to remove ammonia nitrogen and nitrite from the water and maintain good water quality.

Disease prevention and control

1. Ammonia nitrogen poisoning. In high-temperature weather, ammonia nitrogen in the water is high, and nitrite may even be produced, causing bass to die from hypoxia and poisoning. Main symptoms: the whole pond's fish school swims restlessly, darting up and down, fin rays congested, gill filaments dark red. Prevention and treatment methods: immediately inject new water and release old water. When injecting water, use a wooden board to break up the water flow to avoid directly stirring up bottom sediment and accelerating fish death; apply 10—15 kg of fluorite powder (bottom substrate treatment agent) per mu to neutralize ammonia nitrogen in the water; before disease onset, pay attention to using biological preparations for prevention.

2. Enteritis disease. Sick fish have low appetite, swollen abdomen, red and swollen anus, and when lightly pressed, yellow mucus flows out. It can occur throughout the year. The preventive measure is not to feed spoiled small miscellaneous fish. Treatment method: mix 300 g of furazolidone-sulfonamide mixture into every 100 kg of fish paste and feed continuously for 3—5 days.

3. Bacterial gill rot. This disease is prone to outbreaks and epidemics, with high mortality. Main symptoms: the fish body darkens, especially the head, swimming slowly, slow response to external stimuli, difficulty breathing, reduced appetite, increased mucus in the gills, swollen gill filaments, festering at the ends, emaciated body, leaving the group, and finally death. Treatment method: for every 100 kg of fish, use 6—8 g of compound sulfamethoxazole and 4—6 g of chloramphenicol mixed into bait and feed continuously for 3 days.

4. Trichodina, Chilodonella and Scyphidia diseases. They mostly occur on the body surface and gill filaments of fish during the intermediate rearing stage. Symptoms include emaciated fish, darkened body color, festering at the mouth end, and they can occur in all four seasons. For prevention, large water exchanges are mostly used to improve water quality. For treatment, 0•7—1 ppm of copper sulfate and ferrous sulfate mixture (5:2) can be evenly splashed over the whole pond, or 20—25 ppm formalin can be splashed over the whole pond.

5. Red skin disease and ulcer disease. The fin bases of sick fish are congested, red and swollen, scales shed, epidermis rots, and muscles are exposed. This disease mostly occurs in high-temperature seasons. For prevention, large amounts of new water can be exchanged, quicklime 35—40 ppm applied regularly, and the pond dried and exposed to sunlight in winter. For treatment, bleaching powder 1 ppm can be splashed over the whole pond; oral furazolidone-sulfonamide mixture, with 300 g of medicine mixed into every 100 kg of fish paste; intramuscular injection of penicillin, 3000 international units per kg of body weight.

6. Fish louse disease. Fish lice parasitize the gills, skin and fin rays of fish, causing hyperplasia and deformation of gill filament epithelium, inflammatory edema and body surface damage, leading to secondary bacterial infection and death. Treatment method: splash crystallized trichlorfon 0•2—0•3 ppm over the whole pond.