Several Key Periods in Yellow Catfish Farming

I. Broodstock Cultivation Period

1. Broodstock Collection

As broodstock, the fish are required to have bright body color, a plump body shape, a robust physique, and no disease or injury; they should be over 2 winters old, with males over 14.8cm and females over 11.7cm, at a male-to-female ratio of 1:1.5. When selecting male and female broodstock, pay attention to proper identification. The best time to collect broodstock is in the winter of the previous year.

2. Broodstock Cultivation

The collected broodstock can be disinfected by soaking in 2%-3% salt water for 10-15 minutes, then placed in a dedicated pond for cultivation. The pond area should be over 2 mu, with a water depth of about 1.5m; the pond bottom should be flat, the water should have a certain degree of fertility, and the water transparency should be about 30cm. Plants such as Potamogeton and Hydrilla verticillata can be planted in the pond to provide food organisms and habitat for the broodstock; some freshwater shrimp can also be stocked together to make full use of the water body and provide food organisms for the yellow catfish. During the broodstock cultivation period, small fish, small shrimp, or ground snails and mussels can be fed, as well as eel feed combined with animal-based bait such as snails and mussels. During broodstock cultivation, flush the pond with water once every 2-3 days to promote gonadal development of the broodstock.

II. Fry Cultivation Period

Yellow catfish fry, after 20-30 days of cultivation in the breeding pond, can reach the summer-fingerling size of 2-3cm in body length. During the fry cultivation period, the pond area should be 1-2 mu, water depth about 1m, pH 7-8, dissolved oxygen above 5mg/L, and the pond water must be strictly disinfected.

The optimal palatable food organisms for newly stocked fry are rotifers, nauplii, or small cladocerans, so before stocking the fry, manure should be spread over the whole pond at 150-300kg/mu to fertilize the water. When the fry reach 0.9-1.0cm in body length, a small amount of compound feed can be fed, twice a day, with the daily feeding amount accounting for 3%-5% of the total fish body weight; however, fertilization must be carried out in a timely manner so that the fry always have abundant and palatable food organisms.

III. Fingerling Cultivation Period

Fingerling cultivation is the process of growing summer fingerlings of about 2cm in body length to large-size fingerlings of 5-6cm in body length. The cultivation pond should have an area of over 2 mu, with sufficient water source and good water quality, and a stocking density of 10-15 fish/m2.

During the cultivation process, first, scientific feeding is required: because yellow catfish have the habit of feeding in groups, feed trays should be set up in the pond, and feed should be placed on the trays, fed 2-3 times a day, with the daily feeding amount at about 5% of the total fish body weight, and the crude protein content in the feed should be above 40%; second, water should be adjusted in a timely manner, with regular water addition and exchange, reasonable fertilization, ensuring fresh water quality, sufficient dissolved oxygen, and abundant food organisms, and when necessary, turning on aerators to increase oxygen; third, regular disinfection: every half month, disinfect the feed trays with quicklime or bleaching powder, and antibiotics and other drugs can also be added to the feed to ensure the survival rate of the fingerlings.

IV. Grow-out Fish Farming Period

1. Pond-based Main Culture

(1) Pond Selection

Choose scattered small ponds of 2-5 mu, requiring sufficient water source and water quality meeting aquaculture water standards. The pond should have convenient water intake and drainage, a flat bottom, and be able to guarantee a water depth of 1.5-2.0m; at the same time, the pond bottom should preferably be sandy soil, with bottom mud controlled at about 10cm, and good water and fertilizer retention. Finally, each pond must be equipped with mechanical equipment such as aerators and pumps.

(2) Disinfection and Fertilization

Before stocking fry and fingerlings, both new and old ponds must be cleaned and disinfected. Old ponds should have excess mud removed, keeping only 10cm, and be cleared with 150kg/mu quicklime using the dry method to thoroughly kill parasites, pathogens, and wild fish. After drying for 1 week, fill with water to a depth of 80cm; the water inlet should be fitted with 30-mesh silk screen for filtration to prevent wild fish and fish eggs from entering. Apply fermented organic manure to fertilize the water at 150-200kg/mu, and wait until a large number of zooplankton appear in the pond water before stocking fingerlings.

(3) Fingerling Stocking

Large-size commercial fish are welcomed by the market, so large-size fingerlings of about 30g each should be stocked for grow-out farming. The stocking amount of fingerlings can be flexibly determined according to pond conditions, management level, feed supply, and fingerling size; generally, the stocking density of yellow catfish fingerlings of 30g each is about 1500 fish/mu, and about 200 silver carp and bighead carp of 50g each per mu can be stocked in combination. The stocked fingerlings should be uniform in size, bright in color, smooth in body surface, free of disease and injury, with intact fins, and robust in physique; before entering the pond, they should be soaked in 5% salt water for 10 minutes.

Yellow catfish fingerlings are generally stocked in late April each year, and the accompanying silver carp and bighead carp fingerlings should be stocked half a month after the yellow catfish enter the pond, to facilitate the growth of the yellow catfish.

(4) Feed Feeding

In natural waters, the food of yellow catfish is mainly small fish and shrimp, fish eggs, and some aquatic insects and aquatic plants. In artificial farming, fresh live animal bait can be used, such as small fish and shrimp, livestock and poultry processing scraps, etc., and soybean cake, peanut cake, bran, etc. can also be fed. Generally, compound feed is mostly used for domesticated feeding; the feed is made from imported fishmeal, meat and bone meal, blood meal, soybean meal, rapeseed meal, dried fish worms, etc., combined with feed additives. In the early stage of farming, the protein content should be above 35%-45‰, and the crude fat content should be 5%-8%; in the later stage of farming, small trash fish can replace part of the imported fishmeal, and a protein content of 30% and a fat content of about 6% are sufficient. The reference formula is: fishmeal 25%, soybean cake 20%, rapeseed cake 30%, wheat flour 20%, corn flour 3%, minerals 2%, vitamins 0.2%.

(5) Water Quality Regulation

To prevent water aging, in May and June, add water once a month, exchanging 30cm of new water each time; from June to September, exchange water once every half month, exchanging about 15cm each time, maintaining a water depth of 1.2-1.5m. At the same time, adhere to regular disinfection, applying 15ppm quicklime over the whole pond once a month to purify and disinfect the water quality.

Use aerators scientifically based on dissolved oxygen measurements and weather and water quality conditions, keeping dissolved oxygen above 3mg/L.

(6) Disease Prevention and Control

Yellow catfish have a relatively strong disease resistance; as long as water quality is controlled strictly according to requirements and routine disinfection and prevention are done well, diseases rarely occur. Once a disease occurs, it should be diagnosed promptly and accurately, and medication should be used precisely for treatment.

Because yellow catfish are scaleless fish, their tolerance to commonly used drugs is not as good as that of domestic fish, so prevention should be prioritized, and highly effective, low-toxicity drugs should be used as much as possible during treatment. It is recommended to use regular feeding of medicated bait as a preventive measure, feeding oxytetracycline and Chinese herbs such as rhubarb and Isatis root at an addition rate of 0.1%-0.4% for 3-5 days each month. During fishing, stocking, and transportation, try to avoid injuring the fish body, to prevent infection with water mold in early spring and in low-temperature seasons of autumn and winter.

2. Pond Polyculture

When special feed for yellow catfish is not available and there is no sufficient supply of food organisms such as small trash fish and shrimp, yellow catfish winter fingerlings can be polycultured in ponds mainly culturing other fish species, at a stocking density of 80-150 fish/mu. After 5-6 months of farming, winter fingerlings of about 15g each can grow to 100g each, with a yield of about 10kg of commercial yellow catfish per mu.

3. Cage Farming

(1) Farming Conditions

First, carefully make the cages. The cages are made of polyethylene; the mesh size of the netting is generally required to be 2.0-3.0cm, with the bottom mesh at 1.5cm; the cage size should preferably be 12-24 sq m, with a square or rectangular shape and a depth of 2.0m.

Second, place the cages reasonably. The water quality of the water area where the cages are set should be lively and fresh, with relatively high dissolved oxygen. One week before stocking fingerlings, sink the cages into the water so that algae adhere to the cage walls and reduce fish body abrasions. The spacing between cages should be 2-3m; in areas with strong sunlight, a shade cover should be added above the cages.

Third, pay attention to water source and water quality. Sufficient, stable, and pollution-free water source is required; the water depth at the cage site should be above 2.5 meters, and good water quality should be maintained, with water transparency above 30cm and not a large water exchange volume.

(2) Fingerling Stocking

First, the fingerlings must come from production by regular hatcheries, with uniform size, bright body color, no injuries on the body surface, robust physique, lively swimming, and excellent purity; artificially bred fingerlings are best used.

Second, the stocking time for cage farming of yellow catfish is generally around the Spring Festival, when fingerlings begin to be stocked; before entering the cage, the fish body should be soaked in 5% salt water.

Third, the stocking density is generally 100-150 fish/m2. In addition, some blunt snout bream and fine-scaled xenocypris can be appropriately polycultured to make full use of food organisms and purify the cage water quality.

(3) Feed Feeding

First, the feed fed must be fresh, without mold or rancidity; it is best to choose complete feed produced by regular manufacturers, and the feed is best in powder form; when feeding, mix the feed into a paste and place it on the feed tray in the cage. Second, do a good job of domesticated feeding: start artificial domesticated feeding 2 days after the fry and fingerlings enter the cage, and after 5-7 days of patient domestication, normal feeding can begin. Third, feed reasonably: feed 2-3 times a day, with the feeding amount at 3%-5% of the total fish body weight.

(4) Daily Management

First, standardize operations, regularly check fish growth, carefully observe and analyze fish conditions, handle problems promptly, and keep a cage farming log, recording daily water temperature, feeding, feeding amount, dead fish, and disease-related conditions, to help accumulate experience; second, frequently scrub off dirt and attached algae on the cages so that the water body is fully exchanged; third, frequently check the cages and repair any damage promptly, to avoid fish escape or entry of ferocious fish; fourth, as reservoir water levels rise and fall, adjust the cages promptly to a suitable water depth position; fifth, according to market conditions and fish growth, carry out timely periodic harvesting and restocking, to maximize economic benefits as much as possible.

Cage farming of yellow catfish generally begins batch harvesting and sales in early August.