Detailed Explanation of Key Technical Points for Summer Aquaculture Management

In summer, the weather is hot, water temperature is high, fish grow vigorously, water concentration is high, and fish are susceptible to diseases. During the high-temperature season, strengthening management is particularly important.

I. Regulating Water Quality

1. Fill the pond water to the highest water level. Due to evaporation and seepage, new water should be added promptly, generally once every 7-10 days, 10-15 cm each time. If the water source is insufficient, reduce the amount of bait and fertilizer applied on the premise of ensuring water color and transparency.

2. Pond fertilization should be applied in small amounts but frequently. The water color should be maintained as reddish-brown, brownish-green, brownish-blue (dark green), and green, and the water color should be "lively" (with obvious daily color changes); transparency should be controlled at 20-30 cm; when the water color is very dense, bleaching powder or formaldehyde can be used regularly in conjunction with disease prevention to reduce the biomass of phytoplankton (pay attention to changes in dissolved oxygen when applying chemicals). Under high-density culture conditions, the nitrogen content in water is generally high, so phosphorus fertilizer can be mainly applied, with no or little nitrogen fertilizer.

3. Regulate the pH of the pond water to keep the pH value between 7.5-8.5. Quicklime can be applied once every 15-20 days. The dosage is 20-25 kg per mu, dissolved into lime milk and splashed over the entire pond. This improves water quality, precipitates organic matter in the water, reduces the oxygen consumption of organic matter in the pond water, and promotes the growth of phytoplankton.

4. Reasonably configure and use aerators. According to the designed yield, one impeller-type aerator should be equipped for every 5-8 mu. It can both regulate water quality and increase oxygen to prevent fish from surfacing for air. The use of aerators should be based on the patterns of dissolved oxygen changes in water and the function of the aerator, scientifically determining the start-up time and operating duration. The principle of turning it on at noon on sunny days, in the early morning on cloudy days, not turning it on in the evening, turning it on before fish surface for air, and turning it on at midnight during continuous rainy days should be adhered to; the operating duration should be determined based on weather, water quality, fish surfacing conditions, and the load area of the aerator.

II. Strengthening Bait Management

Bait management should follow the "four fixed" principle, namely fixed time, fixed location, fixed quality, and fixed quantity. The amount of bait should be flexibly controlled according to weather, water quality, and fish feeding conditions. Generally, more feed can be given on sunny days, less on cloudy and rainy days, and feeding should be stopped before muggy weather with thunderstorms. When the water color is good and the water quality is fertile and refreshing, normal feeding can be carried out; when the water color is light, the amount of bait can be increased; when the water color is too dense, the amount of bait should be reduced and new water should be added promptly. When fish compete fiercely for food, normal feeding can be carried out; when the number of fish floating to the surface decreases and competition for food is not fierce, the amount of bait should be reduced, and the cause should be investigated; during the treatment period for fish diseases, the amount of bait should be appropriately controlled.

III. Drug Prevention

1. Use bleaching powder once every half month to prevent bacterial fish diseases, splashing over the entire pond to make the pond water 1 ppm.

2. Disinfect the feeding area with bleaching powder once a month, once a day, with 250 grams per feeding point. The method is to dissolve bleaching powder first and splash it around the feeding area before feeding fish at 2:00-3:00 PM every day, then feed the fish. This can be used for 3-4 consecutive days.

3. After entering July, hang bags at the feeding area once every ten days, using the opportunity of fish coming to the feeding area to eat and repeatedly contacting the drugs dissolved from the hanging bags to kill parasites on the fish. Use for 3-4 consecutive days each time, changing the drug once a day. Copper sulfate and ferrous sulfate can be used, with daily dosages of 100 grams and 40 grams respectively. The two drugs should be used at separate times. Hang 4-6 bags at each feeding area.

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