How to Raise Barramundi? A Detailed Guide to Farming Techniques

Barramundi, commonly known as the blind perch, has strong adaptability, a large appetite, fast growth and few diseases, and its flesh is delicious with high nutritional value, making it a major economic fish in Southeast Asia. Because barramundi only takes about 4 months to grow from 3-5 cm fry to the 400-500 g market size, and because it adapts to a wide range of conditions and can be farmed in both fresh water and brackish water, and because it commands a high market price (currently 36-50 yuan per kg) and is in great demand, it is used by the countries of Southeast Asia as well as Taiwan, China and Hong Kong, China as a main species for pond and cage farming, and is one of the valuable economic fish for freshwater and brackish-water aquaculture.
　　
I. Farming Conditions:
1. Pond conditions and supporting facilities: Barramundi likes to live in water that is clear and rich in dissolved oxygen, and it has a certain schooling habit, so the farming pond should be close to a water source, with good water quality and convenient water intake and drainage, and should be equipped with aeration equipment. The area should preferably not exceed 10 mu, with a water depth of 15 m-2 m and little silt; at the same time, convenient transportation is required. One month before stocking, the pond must be cleaned and thoroughly treated (the pond-clearing method is the same as for conventional fish farming). Ten days before releasing the fry, fill with water to 70-100 cm, install a fine-mesh filter at the inlet to prevent other predatory fish from entering, and apply 150 kg of coarse salt per mu so that the pond has a certain “salt bottom”; this is the key to successfully farming barramundi in pure fresh water.
2. Cage farming: The cages are set up in reservoirs and rivers where the water depth is more than 2 m, the transparency is above 30 cm, the dissolved oxygen is 4 mg/L, the pH is neutral or slightly alkaline, and there is slight fresh water flow. The cage area is best 24 sq m per unit, and fixed cages should have a mesh size above 1 cm.
　　
II. Fry Desalination and Nursery Rearing
Intermediate desalination and nursery rearing of the fry is the key technique for freshwater farming of barramundi; it determines whether barramundi farming makes money and whether it succeeds. In the past, the barramundi fry farmed in China mainly came from Thailand, and most farmers chose fry of 5-7 cm or larger. Because there was no intermediate rearing or desalination, the purchased fry were put directly into the pond, so the survival rate of the fry was very low, sometimes only 10%-20%, sometimes a total loss, and at best only 40%-50%, which directly limited the development of this fish's farming in China. It is understood that the low survival rate of barramundi fry after being put into the pond is caused by the following points: First, the hatcheries for barramundi in Thailand are concentrated in southern Thailand, and the fry sent from Thailand to China are generally transported the same day from southern Thailand to near Bangkok airport for water conditioning, then the next morning are repackaged with added oxygen and water and put on a plane to Hong Kong, China, and finally reach the farmer's pond via Shenzhen. The whole process takes at least 13 hours or more, and the long-distance transport with transfers often injures the fry, resulting in a low survival rate after they are put into the pond. Second, when the barramundi fry are transported the same day from southern Thailand to near the airport for water conditioning, because land rent near the airport is expensive and water is scarce, dealers often use very few tanks to hold large numbers of fry, which easily leads to “crowding” of the fry; even if the fry do not die at that time, they begin to die in large numbers 2-3 days after being put into the pond. Third, the barramundi fry imported from Thailand are moved from the “saltiest” seawater (salinity 20‰) directly into pure freshwater ponds without desalination, so the desalination is too rapid. Because the difference in living environment is too great, the survival rate of the fry is low. For the above reasons, the survival rate of the barramundi fry purchased by farmers after being put into the pond is very low, and the actual cost of the surviving fry is very high, which reduces the profitability of barramundi farming. For this reason, at our high-quality fry site in Panyu, we began in 1998 to carry out intermediate acclimation, desalination and rearing of barramundi fry, and achieved success: fry hatched for 15 days after import from Thailand (salinity 15‰) were gradually desalinated and reared over 20-30 days through an acclimation process into large-size fry of 3 cm or more that are fully adapted to pure fresh water and can eat a complete fish-paste diet, with a survival rate above 75%. The barramundi fry now supplied to farmers by the fry base are all fry of 3 cm or more that have been desalinated for more than 20 days, are 100% adapted to pure fresh water, and feed entirely on fish paste.
　　
III. Grow-Out Farming
After about 4 months of careful rearing, most barramundi that have been desalinated to 100% pure fresh water and feed entirely on fish paste and are 3 cm or more in size can reach the market size of 400-500 g.
　　
1. Farming method: Barramundi are cultured specifically in ponds and cages. For pond monoculture, the stocking density is 800-1000 fish per mu. To improve water quality and make full use of leftover feed, 40 bighead carp of 250 g and 100 crucian carp of 50 g can be polycultured per mu. Before the fry are put into the pond, it is best to keep them for 7-10 days in a 200-300 sq m enclosure net in the original pond, and only then remove the enclosure net and transfer them to pond culture. For cage culture, stock 25 fish per sq m; where there is slight flowing water, 30-40 fish per sq m can be stocked in the cage.
2. Feed and Feeding:
(1) Feed types: A. Animal feed such as iced fresh trash fish; B. High-energy extruded feed.
(2) Feeding method and feeding amount: Determine the feeding amount according to fish growth, water quality, weather, feed quality, etc.:
A. For fry just put into the pond, choose trash fish with more meat and fewer bones, grind them into meat paste with a meat grinder, remove the bones, and add a small amount of eel feed to make a mixed feed. Feed three times a day, with a daily feeding amount of 50% of the fish body weight, then gradually reduce it to 20%. In the first 3 days of feeding, it is best to add 5 g of Lidalin and 4 g of oxytetracycline per 50 kg of feed to help prevent disease.
B. After 10 days the fry gradually grow, and feeding should follow the “four fixed” principles. When training them to feed, remove the board first and then feed; when feeding, go slowly at first and then quickly, feed small amounts frequently, and evenly throw the feed within a certain water surface area in rotation so that the feed is swallowed by the fish as soon as it floats on the water surface.
C. When the fry grow to about 15 cm, suitable-sized fish pieces can be cut and fed. When feeding iced fresh fish, the amount is generally 12% of fish body weight, then gradually reduced to 8%-10%. When feeding high-energy extruded feed, the feeding amount should be controlled at 8%-10% of fish body weight, and the feeding amount should be adjusted once every 8-10 days. In short, do not feed spoiled feed, do not feed when fish are short of oxygen, feed less on cloudy and rainy days, do not feed when the fish stop competing for food, feed more when the fish grow fast, and do not interrupt feeding until they reach market size.
3. Rearing management: Barramundi farming requires clear water quality, high dissolved oxygen and transparency above 30 cm, so water must be changed frequently, especially in the peak season. During the whole farming period, quicklime should be used for disinfection 2-3 times, improving water quality while keeping it slightly alkaline. Persist in patrolling the pond morning and evening. For cage culture, check and clean the cages frequently to prevent blocked mesh from causing oxygen shortage. As the fish grow, replace the cages with larger mesh. Careful records should be kept throughout the grow-out period and summarized in time.
4. Fish disease control: If the following diseases occur, handle them as follows:
(1) White spots on the body surface: The fry can be soaked in a 15%-20% salinity solution, or in a 20 ppm formalin solution, for 1-2 hours.
(2) If there are bacterial or parasitic diseases, the following measures can be taken respectively:
A. Saprolegniasis: Bathe with gentian violet at 10 ppm, or splash malachite green at 0.15-0.2 ppm over the whole pond.
B. Parasites (trichodina, dactylogyrus, etc.): Splash crystalline trichlorfon at 0.8-1 ppm over the whole pond.
C. Enteritis: red and swollen anus, congested fin bases, and red spots on the abdomen; feed 3 g of furazolidone per 50 kg of fish, or feed 5 g of sulfamidine, for 3-5 consecutive days.
Whether in pond culture or cage culture, barramundi can achieve relatively good economic returns, and barramundi is a freshwater aquaculture species worth promoting. Barramundi can be fed either iced fresh trash fish or high-energy extruded feed, and the feed costs of the two are about the same. We suggest that ponds with good water sources and good water-exchange conditions can be fed iced fresh trash fish and high-energy extruded feed. For ponds with poor water-exchange conditions or places without iced fresh trash fish, it is best to choose high-energy extruded feed. This is because feeding high-energy extruded feed has the advantages of easy feeding management, labor saving, no waste, no water pollution, and fewer fish diseases.
For freshwater farming of barramundi, be sure to choose fry of 3 cm or more that have been desalinated to 100% pure fresh water and already feed entirely on fish paste, so as to ensure a high survival rate after the fry are put into the pond, ensure that the commercial fish reach the market on time, maximize farming benefits, and avoid farming risks.