Technical points concerning black seabream farming
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**I. Introduction**
**1. Biological Characteristics**
Black sea bream, commonly known as *Pseudosetipinna*, is a marine fish with a streamlined and flat body. Its body length typically ranges from 20 to 30 cm, with a weight between 100 to 300 grams. The head is elongated and pointed, with long mandibles that extend beyond the maxilla. The jaw structure features fine teeth on the vomer and cheekbone, while a dark line runs along the outer edge of the maxilla. The back of the head is low, and the dorsal fin has a pointed shape. The eyes are large and positioned high on the head, with the distance between them approximately equal to the eye diameter. A sharp spine is located at the lower edge of the orbital bone.
The dorsal fin consists of 13 spines and 12 soft rays, while the caudal fin is rounded. The scales are small and round, and the coloration is generally grayish-brown on the back and sides, with irregular black markings. The chest and belly are lighter in color, while the dorsal fin is dark yellow and the other fins are gray-black. This species is primarily found in the western North Pacific, including the Yellow Sea, Bohai Sea, and East China Sea in China, as well as the northern coasts of North Korea, Japan, and the southern Okhotsk Sea. It is a bottom-dwelling fish that prefers shallow rocky areas or seaweed forests, avoiding bright light.
Juveniles typically inhabit waters less than 20 meters deep, while adults move to deeper waters as they grow. During breeding season, they return to shallower waters around 20-30 meters deep. They do not travel long distances but may form small groups during seasonal temperature changes in spring and autumn.
**2. Living Habits**
Black sea bream is cold-tolerant, with an optimal temperature range of 8-25°C. Growth is most rapid between 14-22°C, and feeding ceases when water temperatures drop below 5-6°C. The lethal temperature is 1°C. As carnivorous fish, they feed on small fish, shrimp, shellfish, and cephalopods. In the Yellow Sea and Bohai Sea, their diet includes squid, anchovies, sardines, and various crustaceans. They have a strong appetite, consuming up to 7.5% of their body weight daily, with satiety reached at about 11%.
**3. Growth**
Black sea bream grows rapidly. In cage culture experiments in Changdao County, Shandong, fish measuring 7-18 cm in length grew to an average of 25.5 cm and 485 g within four months. Growth continues through winter and into the next year. Growth rate declines after the 5th instar and drops significantly after the 8th. In Yantai, seedlings can reach 250 g in their second year and 600-800 g by the third. Farmed fish can reach 400 g in two years and 900-1000 g in three.
**4. Breeding Habits**
Black sea bream breeds in early spring, with males maturing at 2-3 years and females at 3-4 years. Spawning occurs between November and December, with eggs developing in the female’s body. Larvae hatch when water temperatures are around 11°C, with peak spawning occurring at 13-16°C. Spawning typically takes place in shallow, flowing waters near the shore. Larvae measure 6.2-7.2 mm at hatching and begin feeding actively. Juveniles grow quickly, reaching 10.25-15 mm in size, and develop hard fins. By July-August, juveniles of 30-50 mm can be caught along the coast.
**Economic Characteristics**
Black sea bream is highly valued for its tender, white flesh with low fat content, making it ideal for steaming and soups. Due to its fast growth and adaptability, it is suitable for both cage and large-scale aquaculture.
**Aquaculture Status**
Main breeding methods include caged farming in Shandong’s Changdao and Rongcheng, where fish can overwinter naturally, reducing costs. The market price is around 40-50 yuan/kg in Beijing and Tianjin. Lianyungang is also preparing for large-scale cage culture.
**Economic Benefit Analysis**
With a 3-year growth cycle, investment per cage is 1,000 yuan, with seed cost at 2 yuan per fish. Feed conversion ratio is 8:1. Total input includes seed (10,000 yuan), feed (14,000 yuan), labor (30,000 yuan), and output (140,000 yuan). Profit reaches 76,000 yuan, showing significant economic potential. However, the long growth period poses a challenge for farmers.
**II. Nursery Technology**
**1. Broodstock Selection**
Artificial and wild broodstock can be used. Younger fish (4-7 years old, 38-45 cm) produce higher survival rates. Stocking density is 3-5 fish/m³, with feeding on small fish and sardines every other day. Water quality must be maintained, and lighting controlled to prevent stress.
**2. Larval Collection**
Larvae are collected using overflow tanks and transferred to rearing ponds. Survival rates depend on larval quality and environmental conditions.
**3. Larval Rearing**
Larvae are fed rotifers, Artemia, and later chopped fish and shrimp. Water quality is managed with sand-filtered seawater and chlorella. Feeding frequency and density vary with larval size.
**4. Post-Cultivation**
Juveniles are moved to secondary ponds or cages when they reach 30-75 mm. Stocking densities and feeding practices are adjusted to avoid overcrowding and disease.
**III. Earthen Pond Cultivation**
Earthen ponds offer a low-cost alternative for seedling production. Muping District in Yantai has developed efficient techniques. Fish can reach commercial size within one year, especially in northern coastal regions due to cold tolerance.
**IV. Disease Prevention**
Diseases are similar to those of related species. Maintaining proper stocking density and feeding live bait are key to prevention.
**V. Conclusion**
Black sea bream is a promising species for aquaculture due to its fast growth, high market value, and adaptability. With proper management and technology, it can become a major aquaculture species in China and beyond.