Taking Control of Fishery Production: Precautions for Raising Fish in Early Spring
Fish Farming
By doing a good job of early spring management of fish ponds, farmers can effectively seize the initiative in fishery production for the whole year, so as to reduce fish farming costs and improve the economic returns of fish farming. We have specially summarized the five major precautions for raising fish in early spring for aquaculture farmers.
1. Applying Additional Fertilizer
In early spring, when the pond water temperature stabilizes at 8°C-10°C, start applying additional fertilizer to cultivate natural food in the water. The amount of fertilizer applied should be determined according to whether the water is nutrient-rich or nutrient-poor and the quality of the fertilizer. Generally, apply 60-90 kg of human excrement and urine per mu, or 100-150 kg of livestock manure. If chemical fertilizer is used, follow a nitrogen-phosphorus-potassium ratio of 1:1:0.5. When applying, first crush it, mix it with water, and splash it evenly over the whole pond. The total amount per mu is 3-7 kg, with each additional application 5-10 days apart, so that the pond water remains yellow-brown or yellow-green, with a transparency of about 30 cm, which is ideal.
2. Feeding
When the water temperature rises to 10°C, the fish begin to feed in small amounts. If multiple small patches of turbidity appear from the bottom of the pond to the surface, it indicates that the fish are in a state of hunger and are highly active. In early spring, fish feeding should be based mainly on concentrated feeds such as soybean cake, wheat bran and cornmeal, fed once a day at a fixed spot and a fixed time, with each feeding amounting to 1.5%-3% of the fish body weight. Later, as the water temperature rises, gradually increase the feeding amount and change to feeding twice a day. The specific feeding amount should also be flexibly controlled according to water temperature, weather and the feeding situation of the fish. At the same time, feeding should be introduced and the fish trained until they can be fed at a fixed spot on the feeding platform, which can improve feed utilization efficiency.
3. Adding Water
In early spring, because the water temperature is low, the fish are small, and their activity and food intake are low, the pond water should not be too deep and should be controlled at 0.6-0.8 m. As the water temperature rises and the fish grow larger, gradually deepen the water level. In early spring, it is best to carry out one major water change, replacing 1/2 of the total pond water. After that, add water once every 15 days, raising the water level by 10-15 cm each time. In March-April, keep the pond water level at about 1 m. At the same time, prevent sewage and harmful organisms from flowing in. If there is continuous rainy weather, appropriately increase the pond water depth to prevent the water temperature from fluctuating too greatly. If the pond water is found to be aging, inject 0.2 m of fresh water into the pond, and apply 20-30 kg of quicklime per mu after slaking it in water and splashing it evenly over the whole pond.
4. Disease Prevention
Long-term hunger in fish can cause stunted growth, reduced physical condition and an increase in disease. To prevent the spread of pathogenic bacteria, when filling the pond in early spring, try to use well water or clean river water. The pond should have dedicated management, with inspections every morning and evening to check whether the water is nutrient-rich or nutrient-poor and to determine the amount of fertilizer and feed to apply. Remove leftover bait promptly, keep the pond water clean, and prohibit feeding spoiled feed. Common fish diseases in adult fish ponds in spring are mainly saprolegniasis, scale protrusion disease and ascites disease. These diseases can be treated by mixing salt and baking soda in water and splashing it over the whole pond or by soaking and washing the fish. Every 15 days, splash the whole pond alternately with 1 mg/L bleaching powder and 0.7 mg/L copper sulfate aqueous solution. If fish are found to be sick, diagnose and treat them promptly. After the fish begin to feed, some medicated bait can be given to improve the disease resistance of the fish.