I. Morphological characteristics

Grouper belongs to teleost, Perciformes, Perciformes, Ophiopogonidae and Ophiopogonidae. The main cultured species in China are snakehead, spotted snakehead and their hybrids, and spotted fish is their common name.

1, morphological characteristics of snakehead The front part of the body is cylindrical and the back part is flat; Generally, it is 25-40 cm long.

The head is long, slightly flat at the front and slightly raised at the back. The body color is gray-black, the back and top of the head are dark, the abdomen is pale, there are irregular black patches on the side of the body, and there are two rows of black stripes on the top of the head. The dorsal fin is very long, almost connected to the caudal fin, without hard spines, starting above the base of the pectoral fin. The ventral fin is short, the pectoral fin is round, and the tip of the fin extends beyond the middle of the ventral fin. The gluteal fin is shorter than the dorsal fin, the caudal fin is round, and the end does not reach the anus. The anus is located immediately in front of the anal fin.

The whole body is covered with medium-sized round scales, and the top of the head is covered with irregular scales. The lateral line is straight, with a slight twist above the anus, moving down two rows of scales, located in the middle of the body side and extending to the caudal base. Fishermen in the Pearl River Delta are customarily called "grouper in two lakes". Fish has a strong smell.

2. The morphological characteristics of spotted snakehead are generally 20cm long and 500-1000g.

The body is nearly cylindrical and the tail handle is thick and short. The head is long, the kiss is short and slightly flat. The base of dorsal fin and gluteal fin is very long without hard spines. The pectoral fin is round, the ventral fin is small, and it is anterior. The caudal fin is round. The body is dark gray, the abdomen is gray, and there are many irregular black spots; The black spot on the top of the head is "September 18th".

Traditionally known as "Guangdong grouper", fish soup has no smell.

3. The main difference between snakehead and snakehead is that snakehead is longer and snakehead is shorter; There are seven-star markings on the top of snakehead head, while the markings on the top of spotted snakehead head are similar to the word "188".

In addition, the head of snakehead is sharp and more snake-like.

4. Offspring hybrid was bred by crossing snakehead with Guangdong spotted snakehead from other places (Shandong, Hunan, etc.). The hybrid grew rapidly, with a weight of about 1 kg in three months, which was characterized by strong stress resistance, tender meat and delicious taste.

In the Pearl River Delta region, snakehead is commonly known as "Hong Kong species", snakehead is commonly known as "Hunan fish", and the first generation of fish bred by crossing two kinds of snakehead is "hybrid"

Second, the living environment

1, Grouper is a benthic fish, which usually lives in still water or micro-flowing water with overgrown aquatic plants and soft sediment, all over lakes, rivers, reservoirs, ponds and other waters, and often dives into the bottom of the water to maintain its balance by swinging its pectoral fins. Grouper has strong adaptability to the changes of environmental factors in water, especially to hypoxia, water temperature changes and poor water quality.

2. When the water is short of oxygen, it can put its head out of the water and breathe the oxygen in the air directly with the help of the branchial device in the branchial cavity. Even in the case of little water or even water, it can survive for a long time as long as the gill and body surface are kept at a certain humidity. The survival water temperature of grouper is 0℃-41℃, and the optimum water temperature is 26℃-28℃.

3. When the water temperature reaches above 8℃ in spring, it often moves in the upper layer of the water body, and it often moves in the upper layer of the water body in summer. When the water temperature drops below 6℃ in autumn, it swims slowly and often lurks in the depths of the water. When the water temperature is too low in winter, it submerges the second half of its body in mud or hay, and its head is exposed in the water and it can't eat. Grouper has a strong jumping ability. When the weather is sultry and rainy, the grouper often jumps out of the water and escapes along the embankment. When there is an impact of running water, it will often arouse the fish to jump and escape. When escaping, the body will move forward slowly like a snake.