Cultivation of Freshwater Whitefish in Ponds in Mountain Areas

During the period from 2004 to 2008, our station conducted a demonstration of high-yield aquaculture in freshwater ponds at the Sanxi Eco-Aquaculture Demonstration Center for five consecutive years. The average yield per acre remained around 450kg without the use of aeration equipment, and the economic returns were impressive. Below is a detailed description of the approach we took: I. Pond Conditions The aquaculture center is located in Sanxi Town, approximately 18 kilometers from Chengguan. It is conveniently situated near the Huishuihe Irrigation Ditch, ensuring a steady supply of clean water. The water source is abundant, with excellent quality and a well-established drainage system. There are no pollution sources nearby. The breeding pond is rectangular, oriented east-west, covering an area of 5 acres with a depth of 1.4 meters. The bottom is flat, surrounded by a concrete slope with a ratio of 1:1.5. II. Pond Preparation Each winter, the pond is drained and exposed to sunlight until April 15 of the following year. At that time, quicklime is used to disinfect the pond. We apply 75 kg of lime per mu. After stocking fish, the water level is adjusted to about 1.1 meters after 10–15 days. III. Stocking of Fish Seeds 1. Stocking Time: Freshwater whitefish is a tropical species that cannot tolerate low temperatures. Therefore, stocking is only done when the water temperature remains above 20–22°C. The ideal time is mid-May, but not later than the end of May. It’s best to stock on a sunny day during noon. 2. Source and Selection: The fish seeds come from the suburban fishing grounds of Hefei. These fish, raised using waste heat from a thermal power plant, are strong and well-proportioned. 3. Stocking Density and Size: Based on the advantages of freshwater whitefish and the pond conditions, we stocked 800 fish per acre. The size was 14–16 kg per fish. Before stocking, they were soaked in a 3%–5% salt solution for 5–8 minutes and then placed in the pond for 1–2 hours. To improve water quality and utilize space, we also introduced squid species at a ratio of 6:1 (10–15 tails per acre). IV. Feeding Practices 1. Fixed feeding points help monitor the fish's feeding behavior. 2. Feeding times are set at 9:00, 11:30, 14:30, and 16:30 daily. Pellet feed is given at 9:00 and 14:30, while a mix of soybeans and corn is provided at 11:30 and 16:30. 3. Feed quality is crucial—only fresh, non-moldy feed is used. Main feed types include soybeans, corn, wheat, rice bran, vegetable cake, watermelon rind, animal carcasses, and slaughterhouse by-products. 4. Feeding quantity is determined based on growth rate, season, and weather. Fish weight is measured every 10–15 days, and feeding rates are adjusted accordingly. Typically, the initial feeding rate is 3–4%, increasing to 4–6% during the middle phase, and up to 7–8% in the later stage. V. Daily Management 1. Water Quality: Every 15 days, 15–20 cm of water is replaced. During hot summer months (July–August), more water is added every 5–10 days to maintain good oxygen levels. 2. Pond Patrols: Morning and afternoon patrols are essential to observe fish behavior, feeding activity, and water conditions. Special attention is given during hot afternoons or thunderstorms. Any abnormalities must be addressed promptly. 3. Disease Prevention: Although freshwater whitefish has strong disease resistance, preventive measures are still necessary. - Bacterial diseases can be prevented by applying 5–7.5 kg of lime per mu. - Floating heads are prevented by adding fresh water daily during summer to increase dissolved oxygen. VI. Key Techniques for High Yield 1. When stocking, ensure fish sizes are consistent and not too small. 2. Avoid stocking bottom-dwelling fish in the main pond, as this may reduce yield. 3. Stocking should occur in mid-May when the water temperature stabilizes at 20–22°C. Early stocking may cause temperature fluctuations, reducing survival rates, while late stocking affects growth and market readiness. 4. Freshwater whitefish has a strong appetite, so feeding should follow the “four set” principle—small amounts, multiple times, and avoid overfeeding.

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