What kind of fish is the red drum? Breed characteristics and farming techniques

Breed name: red drum

English name: redfish

Common names: redfish, red croaker, spotted tail fish, channel bass

Scientific name: Sciaenops ocellatus

Biological characteristics

(1) Morphological characteristics

The red drum is spindle-shaped, laterally compressed, with a slightly raised back that is highest at the origin of the dorsal fin. The head is medium-sized, the mouth cleft is relatively large and terminal, and the teeth are small, closely arranged and fairly sharp. There are two pairs of nostrils, the rear pair oval and slightly larger. The eyes are dorsolateral, with the posterior margin level with the end of the mouth cleft, medium-sized, and located on both sides of the head. The posterior margin of the preoperculum is serrated, and the margin of the operculum has two pointed tooth-like protrusions. The scales are ctenoid, the lateral line is obvious, the back is light black, the scales have a silvery sheen, the middle of the belly is white, the sides are pink, the caudal fin is black, and the most obvious feature is a black round spot above the lateral line at the base of the tail. The total length is 2.65-2.7 times the body height.

(2) Living habits

Red drum like to gather in schools, swim quickly, and have obvious migratory habits. They are eurythermal and euryhaline fish, with a suitable temperature of 10-30°C, optimally 18-25°C, but reports say they can tolerate a low temperature of 2°C. They adapt to a very wide salinity range and can grow and develop normally in freshwater, brackish water and seawater. Red drum are carnivorous omnivorous fish, and their position in the food chain is relatively high. In natural waters they mainly feed on shellfish, cephalopods, small fish, etc. Under artificial rearing conditions they also eat artificial compound feed. Red drum grow fast. In their place of origin, individuals in the same year can reach 500-1000 g, and the largest individuals can actually reach 3000 g. Under artificial farming conditions, one year of farming in Taiwan, China can reach 1000 g. In the Qingdao and Lianyungang areas, they can reach more than 500 g in one year.

(3) Reproductive habits

Male red drum can reach sexual maturity at 4 years of age, and females at 5 years or older. Generally, for artificial breeding, broodstock should be male fish over 4 years old and female fish over 5 years old, as this can yield large quantities of eggs and a high fertilization rate. Red drum have a relatively large egg-carrying capacity, generally 50,000-2,000,000 eggs, with some reaching more than 3,000,000 eggs, and spawning is released in batches. They can continue spawning for a period of time. The eggs are pelagic, with a diameter of 0.9-1.0 mm. At 23-25°C, they hatch in about 24 hours, and within 3 days after hatching they grow on yolk nutrition.

Economic traits

Red drum grow fast, have high farming yields and good market prices. Generally, in the Qingdao and Lianyungang areas, they can be grown to 500-750 g marketable fish in the same year, with a maximum yield per mu of 1600 kg. On the domestic market the price is 60 yuan/500 g. Artificial farming of red drum has many advantages, such as wide suitable temperature and salinity ranges, strong tolerance to low oxygen, widely available feed sources and mature fry-rearing technology, and is well worth promoting locally.

Current farming status

The First Institute of Oceanography of the State Oceanic Administration first introduced 8 mm red drum juveniles from the United States in 1991. After one year of indoor intensive rearing, each fish gained an average of 400 g. During the three years from 1992 to 1995, each fish gained an average of 1000 g per year. The adult fish began to spawn in 1995. Pond farming began in 1996. At present, red drum have been widely promoted to the coastal provinces and cities of our country. Gaogongdao Township in our city first introduced 2000 fry from Qingdao in 1997 for shrimp pond and cage farming and achieved good results. Red drum farming has relatively high economic benefits.