Commercial farming process for squarehead catfish.

(Baonghean) - Squarehead catfish is an easy-to-raise fish species with a fast growth rate, delicious meat, and high economic efficiency, thriving in the Mekong Delta and Southwestern provinces. In Nghe An, recently, the Nghe An Fisheries Department successfully conducted trial farming of this species through the project "Applying scientific and technological advancements to build a commercial farming model for squarehead catfish in Nghe An". The project has completed the process of commercially farming squarehead catfish in Nghe An:



Squarehead catfish at the time of harvest.

1. Prepare the fish pond.

- Pond conditions: The pond should have an area of ​​1,000 - 5,000 m2, a depth of 1.4 - 2 m, a bottom mud layer of 15 - 20 cm, a soil pH of 6.5 - 8, and sturdy pond banks with active water supply and drainage systems.

- Pond renovation: Drain the pond, clean the surrounding banks, fill in any leaks or holes, level the pond bottom, apply lime for disinfection and weed control at a rate of 7-12 kg/100m2, and dry the pond bottom for 2-3 days.

- Creating the desired water color: After filling the pond with water to create the desired color, use 2-3 kg of NPK per 100m² and spread it evenly throughout the pond to provide an initial food source of algae and plankton for the fish.

- Water intake: The water source must be clean, free from disease and pollution. The water is filtered through a net to prevent predators and unwanted fish from entering the pond. Fill the pond with 1.2 - 1.5 meters of water 2-3 days before stocking the fish.

- Stretch a net around the edge of the pond to prevent the fish from escaping.

2. Release the seeds.

Seed quality: Select healthy individuals, free from abrasions, deformities, or defects, swimming actively, with bright, uniform coloration, without loss of mucus, and swimming in schools. Choose the correct species of squarehead catfish. Stocking size: 300 - 350 fish/kg. Density: 20 - 40 fish/m2.
Before releasing the fish fry, they must be bathed in a 15-30‰ salt solution for 15-30 minutes.

3. Care and management

- Feed: Use commercially produced pelleted feed with a protein content of 25-30%. The conversion ratio of commercially produced feed is 1.6-1.8. Periodically supplement with vitamin C and minerals at a rate of 5g/1kg of feed, mixed into the feed, to increase the fish's resistance. The feeding rate is 2-4% of body weight, depending on the weight and growth stage of the fish. Feed the fish twice a day, at 8-9 am and 4-5 pm.

- Water quality management: During the farming process, it is necessary to regularly monitor the water quality to maintain stability and cleanliness. When the water color is pale, apply inorganic fertilizer at a rate of 1.5-3.0 kg nitrogen and 0.8-1.5 kg phosphorus per 1,000 m2 of pond area, adjusting the dosage according to the water color and applying it during cool weather. After fertilizing, observe the water color to avoid over-fertilization which can cause water pollution. Regularly change the water to create a flow in the pond to prevent dirty water and fish diseases. Always maintain water clarity at around 35 cm. Regularly check the pH, keeping it around 7-8. If the pH decreases, use Zeolite to stabilize it at a rate of 7-10 kg per 1,000 m2. Periodically, every 15 days, use lime to treat the pond water environment at a rate of 2-2.5 kg per 100 m2 of pond area.

4. Preventing and treating fish diseases

Squarehead catfish are relatively disease-resistant. However, some common diseases include bloating, blackening of the body, acute hemorrhage, fungal infections, and ulcers. These outbreaks are caused by improper feeding practices, polluted pond environments, or poor quality feed.

To prevent these diseases, it is necessary to adjust the feed ration and the number of feedings per day accordingly, maintain the quality of the pond environment, periodically disinfect the pond environment, and especially supplement with vitamin C.

When fish are sick, it is necessary to correctly diagnose the type of disease (fungus, parasite, worms, flukes, bacteria, etc.) in order to use the right and appropriate medications, treat them promptly, and combine this with water environment treatment to limit the spread of pathogens and avoid mass fish deaths.

5. Harvesting and preserving fish

a. Harvesting

To achieve high harvesting efficiency without affecting the quality of marketable fish, the following methods are commonly applied:

- Selective harvesting: For commercially farmed squarehead catfish, the larger the fish, the higher the price. Therefore, it is possible to selectively harvest the larger fish first, leaving the smaller ones to continue growing. This selective harvesting method can be done using nets.

- Overall harvesting: For ponds where fish have reached a large, uniform size, proceed with overall harvesting. Stop feeding the fish 1-2 days before harvesting. Use nets to remove excess fish 1-2 days before draining the water. Drain the pond completely before continuing with the harvest.

b. Product storage

Squarehead catfish, after harvesting, must be kept alive to increase product value; therefore, thorough preparation is essential before harvesting. It is necessary to contact and schedule delivery dates with the purchasing facility. Prepare equipment and a suitable location for storing the fish during harvesting, ensuring clean water and aeration to increase the survival rate after harvesting and overall sale. Harvesting must be done gently to avoid injury, which can easily kill the fish. They should be quickly transported to the storage area; any dead fish should be promptly cleaned and refrigerated.

Ta Quang Sang (Nghe An Fisheries Department)