Key Technical Points and Daily Management Methods for Fish Farming in Reservoirs
Under normal circumstances, reservoirs have low water levels during the winter and spring dry seasons, and water levels rise after storing and supplying water during the flood season, with relatively large fluctuations in water level, and these fluctuations directly affect the size of the water surface in the reservoir area. The water quality of reservoirs is generally very fertile, which provides excellent conditions for fish farming. Let's take a look at the relevant techniques for reservoir fish farming together below!
1. Reservoir selection. The reservoir is best located in a leeward spot with sufficient sunlight, with the dam and reservoir bottom not leaking, fish-blocking grates or nets installed at the spillway and drainage pipes, and trees, stumps and other debris on the reservoir bottom cleared away. For reservoirs where conflicts over water between agriculture and fish farming may occur, a minimum water level line for protecting fish must be determined, with road access and electricity access.
2. Store water as early as possible. Reservoir water mainly comes from rainfall, so pipes must be plugged to store water as early as possible, ensuring that by no later than the end of March there is enough water to stock fish fingerlings.
3. Apply base fertilizer well. Fertilization should follow the principle of not polluting water quality. Before stocking fish fingerlings, apply a full 200-400 kg of livestock and poultry organic fertilizer per mu. For dry ponds, pile it in several heaps at the shallow water areas of the reservoir bottom and side slopes to ferment, allowing the nutrient-rich water to diffuse freely; for reservoirs already holding water, dig several small soil pits at the reservoir edge to pile the organic fertilizer for fermentation before applying it; fermented organic fertilizer can be directly splashed into the reservoir. It is best to apply sufficient base fertilizer before disinfection.
4. Stock fingerlings at the right time and reasonably. Around the Spring Festival is the best season for stocking fish fingerlings in reservoirs, because at this time the reservoir water level is relatively low, water temperature is relatively low, and fish scales are tight, which facilitates fishing operations and transportation, makes fingerlings less prone to injury and infection, and results in a high survival rate in farming. Stocking large-sized, multi-variety, sufficient high-quality fingerlings is the key to achieving high yields in reservoir fish farming. The stocked black carp, silver carp, and bighead carp should be 9 fish/kg or more, and crucian carp and bream 15 fish/kg or more. To eliminate wild and miscellaneous fish, stock 80 largemouth bass per mu. The stocking amount of fingerlings should be determined according to reservoir conditions, but must not exceed the carrying capacity of the water body; rational dense stocking should be used, and fingerlings should be stocked all at once in sufficient quantity, generally 500-800 fish per mu.
5. Apply supplementary fertilizer skillfully. From April to October, try not to apply organic fertilizer to reduce the occurrence of fish diseases, and instead apply inorganic fertilizer. Ammonium bicarbonate and superphosphate are preferred as inorganic fertilizers, with a required fertilization amount of 3 kg/mu, once every 15 days, flexibly increased or decreased according to water quality, weather, and water temperature, keeping the water tea-brown, grass-green, brown-yellow, or sauce-red, with significant morning, noon, and evening water color changes, and maintaining transparency at about 40 cm. Supplementary fertilization should avoid periods of heavy rain to prevent the nutrient-rich water from being lost with floodwater and going to waste.
6. Feed scientifically. The overall guiding idea for feeding bait is to "grasp both ends and focus on the middle," that is, in early spring and late autumn, focus on feeding concentrated feed with a small amount of bait, while the main feeding focus is in June-September during the peak growth season of fish, when both the quantity and quality of bait are required to be higher. In spring, put in live bait such as river snails all at once, at 3000-5000 jin of river snails per mu. In early spring and late autumn, mainly feed compound pellet feed or cake and meal-type bait, once a day; from June to September, feed twice a day, once in the morning and once in the afternoon, first feeding grass, then compound feed or cake and meal-type feed. At the same time, operate feeding according to the "four fixed" (fixed quality, fixed quantity, fixed time, fixed location) and "three looks" (look at weather, look at water quality, look at the fish's feeding situation) methods.
7. Adjust water with quicklime. Newly built reservoirs for fish farming have muddy water, which affects fish respiration and the reproduction of plankton. Splashing quicklime once every 20-30 days has a good effect of settling mud and clearing water, and also plays a role in preventing fish diseases. The dosage is 20-30 kg per mu each time, dissolved in water and splashed over the water surface.
8. Improve the environment. When the reservoir water level gradually decreases, the reservoir drawdown area can be fully utilized; each time the water level drops a little, sow some seeds, mainly Italian ryegrass. Italian ryegrass, Sudan grass, and others can also be planted on the dam surface, side slopes, and the hillsides on both sides, which can not only serve as green feed for fish but also prevent soil from being washed into the reservoir by rainwater and causing turbid water.
9. Reduce seining. Trawling operations very easily stir up the bottom mud and cause turbid water, so trawling should be avoided as much as possible; if trawling is truly necessary, it is best to choose nets with few sinkers.
10. Do a good job in fish disease prevention and control, adhering to the principle of "prevention first, with prevention more important than treatment." Fingerlings should be disinfected when stocked; soak stocked fingerlings in 4% salt water for 15 minutes. Regularly splash disinfectants such as trichloroisocyanuric acid and dibromohydantoin around the feeding area, frequently apply quicklime to raise the pH value, promote the circulation of substances in the water body, improve water quality, and help fish growth and inhibit the occurrence of fish diseases. Generally, use 20 kg per mu each time, mix with water, and splash over the entire reservoir, about once every 20-30 days. When fish diseases are found, apply the right medicine promptly for treatment. The use of prohibited drugs is forbidden. When using drugs, pay attention to the drug instructions to prevent drug damage and cause economic losses.