Sharing Experience and Methods for Using Chemical Fertilizers to Fertilize Water for Fish Farming

With the continuous development of the aquaculture industry today, fish farming in rural areas is relatively common. First of all, because the investment cost of fish farming is low, as long as you have a pond and then buy some fry, you can start down the road of fish farming. In fact, the market demand for fish is also relatively large, and there is no need to worry about selling them.

Experience in Using Chemical Fertilizers to Fertilize Water for Fish Farming

Fertilizing with chemical fertilizers for fish farming does not mean the fish directly eat the chemical fertilizers. Rather, after chemical fertilizers are applied to the water, they increase the nutrient elements in the water body and promote the massive reproduction of aquatic organisms such as phytoplankton and zooplankton, and after the fish eat the above aquatic organisms, the yield increases by a large margin.

1. Scope of application. This technique is not only suitable for large and medium-sized waters such as beaches and lakes with areas of thousands or tens of thousands of mu, but is even more suitable for promotion in small water surfaces such as weir ponds and fish ponds of less than 1 hectare. 2. Climatic conditions for applying chemical fertilizers. Generally, apply from May to October on sunny days with sufficient sunlight and a water temperature above 20 degrees C. The daily application time is from 9 a.m. to 2 p.m. Chemical fertilizers should not be applied on cloudy days, rainy days, or at low temperatures. 3. Types of chemical fertilizers applied in stages and their proportions. Mainly nitrogen and phosphorus fertilizers are applied, and potassium fertilizer is not needed. Nitrogen fertilizer is mainly ammonium bicarbonate, followed by urea, ammonium chloride, etc.; phosphorus fertilizer is mainly superphosphate; nitrogen-phosphorus compound chemical fertilizers can also be applied. The ratio of nitrogen to phosphorus fertilizer is generally 1:1. The amount applied each time per mu should preferably be controlled below 10 kg; the total amount of fertilizer applied depends on the number of fish species in stock. 4. Stocking of fry. The fish species are mainly silver carp and bighead carp, which should account for more than 90% of the total number of fish, while other fish such as carp, crucian carp, and Xenocypris account for less than 10%; fry are generally suitable at about 150 grams per fish, and the number of fry depends on the designed yield. 5. Fertilization method. Choose an open, sunny fertilization area with a water depth of 0.5-4 m, and insist on mixing with water and sprinkling evenly; dry broadcasting and putting in whole bags are opposed. It is also necessary to flexibly manage according to different conditions such as water conditions, fish conditions, and weather changes, and to do a good job of regulating the water in the beaches. 6. Benefit analysis. Fertilizing beaches with chemical fertilizers for fish farming has low input, high output, great benefits, and simple operation. As long as this technique is correctly mastered, generally about 2 kg of chemical fertilizer can increase production by 1 kg of fish, and the chemical fertilizer cost per kg of fish is about 1 yuan.

Choosing the Location for Fish Farming  

Generally, the water quality of rivers suitable for fish farming should have no serious pollution, and the dikes and dams on both sides of the river should be sturdy and not affected by disasters such as floods. There should be few inlets and outlets in the river, and it must be ensured that fish do not escape from these inlets and outlets. In addition, the river bottom should be relatively flat, which is convenient for management and fishing. The annual water level fluctuation should be relatively small, preferably not exceeding 2 m, and the water depth during the fish farming season must not be less than 0.8 m. The water flow speed should not be too high, preferably within 0.5 m per second. There should be relatively abundant aquatic organisms in the river or in waters adjacent to the river, and they should be able to be used relatively conveniently. It is also necessary to understand the surrounding farmland irrigation, water storage, flood discharge, and other conditions, and when building fish-blocking facilities and farming fish, resolve the conflicts between fish farming water use and water conservancy.

Stocking of Fish Species  

For extensive river farming, stock 200-300 fish per mu of water surface, and for intensive river farming, stock 300-500 fish per mu, then adjust according to the fish growth situation at the end of the year. Rivers with relatively fertile water quality should mainly stock silver carp and bighead carp, usually accounting for 70% (bighead carp : silver carp = 6:4), plus 30% black carp, grass carp, bream, and carp (black carp and grass carp account for 5-10%, and carp, crucian carp, and bream account for 10-15%). The stocking time is generally winter, because the winter temperature is low, fish species are convenient to transport, and the survival rate after stocking is high. In addition, natural food in the river is abundant, and growth can be accelerated after stocking.  

Before stocking fish species and before large-scale winter fishing, special attention should be paid to checking whether the fish-blocking facilities have any fish escape openings. On ordinary days, the height of the foil gate should be well controlled, and it should be ensured that it is regularly exposed 8-10 cm above the water surface. If the weather changes or there is a major flood, attention should be paid to adjusting the foil gate. On ordinary days, debris in front of the fish-blocking facilities should be frequently removed to keep the water flow smooth, and the fish-blocking facilities should be checked and repaired at any time, with relevant repair materials kept ready at all times. 

Pond Fish Farming Techniques  

Pond fish farming is the fish farming method used in most areas of China, and currently its output accounts for more than 60% of freshwater fish farming. It has the characteristics of small investment, large returns, quick results, and stable production.  

1. Area: Generally, the area of an adult fish pond is 5-10 mu, which makes it easier to manage. Parent fish ponds, fry ponds, and fingerling ponds are preferably 3-5 mu.  

2. Water depth: Generally, the water depth of an adult fish pond is 2-3 m. In the north, overwintering ponds are preferably 1.5-2 m below the thickest ice layer in severe cold. The water depth of fry ponds and hatching ponds is preferably 1.0-1.5 m. Fingerling ponds generally require a water depth of 1.5-2.0 m.  

3. Water quality: Abundant water sources and good water quality are the fundamental conditions for fish farming.  

4. Requirements for bottom soil: The pond bottom soil is best loam or sandy loam, followed by clay. 

Although fish farming is a relatively simple matter, if the methods are inappropriate, not only will it be impossible to make a profit from it, but hard work and sweat will also be wasted in vain. Therefore, in the process of fish farming, it is also necessary to constantly summarize and continuously develop new fish farming techniques.