Detailed Explanation of Loach Rice Field Farming Methods and Key Technical Points

  The loach is a widely distributed small warm-water bottom-dwelling fish, characterized by a wide suitable temperature range, tolerance to low oxygen, and omnivorous feeding habits. Its flesh is tender, its flavor is delicious, and it has considerable nutritional and medicinal value. On the international market, the loach is called "ginseng of the water."

  I. Key Technical Points

  1. Selection of rice fields for fish farming: fresh, pollution-free water quality, abundant water supply, convenient drainage and irrigation, solid field ridges that do not leak, an area of 2-10 mu, preferably low-lying rice fields that can maintain a certain water level, with clay soil.

  2. Construction of field works and anti-escape facilities: raise and widen the field ridges to a height of 50cm, a bottom width of 50cm, and a top width of 40cm. On the field ridges, use plastic film or gauze netting as anti-escape facilities, with the film or net extending 20cm above the ridge surface and buried 10cm underground. After the rice field is plowed, dig a ring ditch 30cm deep and 20cm wide at a distance of 50cm from the inner side of the field ridge, and trim the ring ditch after transplanting the rice seedlings. The water inlet and outlet use fine-mesh iron wire netting or nylon netting to make fish-blocking grates.

  3. Fertilization of the rice field: apply heavy base fertilizer before transplanting, applying 250Kg of chicken and pig manure per mu to propagate natural bait and promote loach growth. After rice transplanting is completed, apply additional chicken and pig manure at 25kg per mu every 15 days until mid-August.

  4. Scientific pesticide application: the best time to apply pesticides is 3-5 days before transplanting or 5-7 days after transplanting. For weed control in fish-farming rice fields, use low-toxicity, high-efficiency pesticides, such as: Starane and oxadiazon.

  5. Loach stocking: the main source of loach fry is wild fish purchased from suppliers. The stocking size is 5-20cm, with an average of 15kg of fish stocked per mu. In order to better determine the optimal stocking size for loach, increase yield, and boost economic returns, we conducted a comparative experiment stocking two sizes of loach: 5-8cm and 15-20cm.

  6. Feeding management:

  (1) Water quality management: keep the water quality in the field fresh and add new water in a timely manner. After fry are stocked, keep the water depth in the rice field at 5cm or more. In the mid-stage of farming (around mid-July), which is the high-temperature season, the field water depth should be kept at 10cm or more. During the farming period, change the water once every 3-5 days. During daily inspections, if loach are found gasping at the surface, startled, or still not sinking after sunrise, change the water immediately.

  (2) Bait management: to achieve high yields in rice field loach farming, in addition to base fertilizer and topdressing, bait should also be fed every day. In the early stage, feed at 1-1.5% of fish body weight; in the mid-stage, the feeding amount is 3% of fish body weight; in the late stage, the feeding amount is 3-5% of fish body weight. Mainly feed plant-based bait, such as: wheat bran, rice bran, etc. Feeding is generally carried out in the evening, with the full amount given at one time. On cloudy days and days with low atmospheric pressure, the feeding amount should be reduced.

  (3) Daily management: persist in frequent field inspections, checking whether various facilities are damaged. Especially on rainy days, strictly inspect the water inlet and outlet openings and the embankments.

  II. Summary

  1. The optimal stocking size for loach was determined.
  Stocking 5-8cm loach aims at their own weight gain; stocking 15-20cm loach aims at self-reproduction and weight gain. The experimental results show that stocking 5-8cm loach gives better harvest results, with basically 100% reaching adult loach size.

  2. Loach recapture techniques.
  (1) Start harvesting early, catching the large ones and leaving the small ones. We began setting traps in early August to catch large-size loach. This is because: ① large-size loach have strong feeding ability and are easily lured by bait into the traps; ② after loach grow to a certain stage, their weight gain slows; ③ it improves the living environment of loach in the rice field, which helps increase the growth rate of small fish.
  (2) Trapping bait. When setting fish traps to catch loach, in the early fishing period, place loach bait in the fish traps, such as wheat bran, bran, potatoes, animal offal, etc. In the mid and late fishing periods, continuously improve the quality of the bait to make it better suit the loach's taste. We adopted methods such as adding sesame oil to the bait, using roasted red earthworms or sunflower seed cake mixed with chives, and roasted wheat bran and rice bran to lure and catch them.
  (3) Minimum water temperature for fishing. Before harvesting, we frequently measured the temperature. Through two years of practice, we believe that the harvesting temperature for loach in northern regions should be above 15 °C, rather than around 10°C as generally recognized in some technical materials.

  Through the implementation of the above recapture techniques, good harvesting results were achieved, with a recapture rate of over 70%.

  3. Loach anti-escape techniques.

  During the farming process, the "step" anti-escape method was summarized and tested, with very good results. That is, build another step on the inner side of the field ridge. It is 20cm wide and 15cm lower than the field ridge. When loach leap onto the step, it is very difficult for them to leap onto the field ridge again, thereby achieving the purpose of preventing escape.