Detailed Explanation of Summer-Fry Rearing Techniques for Jiang Yellow Catfish

1. Pond Conditions

The pond area should preferably be 1-3 mu, with a water depth of 1.0-1.5 m, rectangular, oriented east-west. The bottom silt should not exceed 10 cm, the pond embankment should be firm and not leak, and its height should exceed the highest water level by 0.3-0.5 m. The pond bottom should be flat and sloped toward the drainage outlet, with ample water supply and convenient water intake and drainage.

2. Preparation Before Fry and Fingerling Stocking

20-30 days before fry stocking, drain the pond water and sun-dry the pond, remove weeds and debris from the pond, and clean up the bottom silt. About 15 days before stocking, add 5-10 cm of water, and use quicklime to disinfect and clear the pond with water, at a rate of 75 kg per mu. The method is: dig several small pits in the pond bottom, pour the quicklime into the small pits respectively and add water, and when a large amount of heat is released, splash it evenly over the pond. The next day, use an iron rake to move the bottom mud so that the lime slurry and the bottom silt are fully mixed, to achieve the purpose of thoroughly clearing the pond. After 7-8 days, wait until the efficacy of the medicine has dissipated, then add water. The intake water must be filtered with a fine mesh net to prevent harmful organisms from entering the pond with the water. 1-2 days after adding water, manure fertilizer can be applied, 200-300 kg per mu, to cultivate large numbers of rotifers. Note that the manure fertilizer must be fully decomposed and fermented before use. When the rotifers have multiplied in large numbers, the Jiang yellow catfish fry can be stocked into the pond. If there are harmful organisms such as frog eggs and tadpoles, they should be removed promptly.

3. Fry Stocking

(1) Source of fry. The Jiang yellow catfish fry are high-quality fry self-bred by this farm, after about 10 days of rearing in observation ponds.

(2) Stocking time. According to the number of rotifers in the pond, choose to stock when the rotifers peak, that is, when water fleas form clusters but are not red.

(3) Stocking method. Since we take the fry from our own farm, we use disinfected buckets for short-distance transport, transport them to the upwind bank of the pond, and pour the fry into the pond in water more than 2 m from the edge. However, if transporting with oxygen bags for fry, first place them in the pond water, also choosing an upwind spot 2 m from the bank, and when the water temperature inside and outside the bag is basically the same (usually about 15 minutes, with a temperature difference within 1°C), the fry can be released. Usually, Jiang yellow catfish fry are reared to summer fry at a stocking rate of about 50,000 per mu.

4. Feeding

2-3 days after the fry are stocked into the pond, the peak period of rotifers has passed, and follow-up feed can be supplemented. According to the fertility of the water, in a corner of the pond far from the water inlet, hang an appropriate amount of fully decomposed and fermented manure fertilizer with a fine mesh net to continuously provide rotifers and various large cladocerans and copepods.

About 15 days after stocking into the pond, the feeding habits of the juvenile fish begin to change, gradually transforming into omnivorous fish mainly feeding on animal feed. At this time, they can be gradually acclimated to artificial compound feed. The feed has a crude protein content of 39.5% and an animal protein content of about 70%.

When starting acclimation feeding, set up 4 feeding tables in the pond and feed 4 times a day, which can be set at 6:00, 10:00, 14:00, and 18:00. When feeding, add water to the cooked powdered feed and mix it into balls, place them on the feeding tables, frequently observe the residual feed, and judge the feeding situation of the fish. When a large number of fry are feeding, reduce the feeding tables from 4 to 2, located on the same side of the pond, and then after another 2-3 days reduce to 1, implementing fixed-point feeding. When the fry grow to 4 cm, pellet feed can be fed, with a pellet diameter of 1 mm. Later, as the fish body grows, gradually increase the feed particle size. At this time, the feeding frequency can be reduced to 2 times: feed 1/3 at 9:00 and 2/3 at 18:00. At the start of feeding, use 1 kg per mu, then gradually increase to 2 kg. The feeding amount should also be determined according to the specific conditions of the day. The general principle is the "four fixed" feeding method.

5. Daily Management

Persist in patrolling the pond every day, pay attention to changes in water quality, regularly add or change water, and maintain the water body as "fresh, fertile, lively, and crisp." If harmful organisms such as crayfish are found in the pond, remove them promptly; crystal trichlorfon can be dissolved in water and splashed over the whole pond. In addition, frequently check whether the fish have fish diseases and prevent and treat them promptly.

6. Results

After about 45 days of rearing, when the Jiang yellow catfish fry are sold by seine netting, the average body length grows to 7-8 cm, and the survival rate reaches more than 85%.