Not the same kind of fish.

Difference:

A, appearance characteristics are different:

1, grouper

Grouper body oval, lateral compression, head large, short and bluntly rounded kiss, mouth large, with a well-developed laying on the bone, the body clad in fine pectin scales, dorsal fins strong, body color can change with the environment. Adults are usually 20 to 30 centimeters in length.

2, blackfish

Blackfish body is cylindrical in the front and later laterally compressed. The head is long, slightly flattened at the front and slightly elevated at the back. The muzzle is short and rounded, the mouth is large, end position, the mouth cleft is slightly oblique and extends to the lower edge of the back of the eye, the lower jaw is slightly protruding. Body color is grayish-black, dorsal and cephalic colors are darker, the abdomen is pale white, irregular black patches on each side of the body, and 2 rows of black markings on each side of the head. The odd fins are spotted with black and white, the even fins are grayish yellow with irregular spots. The entire body is clothed with medium sized scales, round scales, and the top of the head is covered with irregular scales.

Second, the habitat is different:

1, grouper

Grouper inhabits the tropical and temperate oceans, preferring to inhabit in the coastal islands near the rocky reefs, gravel, coral reef substrate of the sea area.

2, blackfish

Blackfish is a freshwater benthic fish, usually inhabiting the water grass or silt substrate in the waters of rivers, lakes, reservoirs, ponds, paddy fields and other waters.

Three, different habits:

1, grouper

Grouper like quiet afraid of waves, like warm afraid of cold, like clear afraid of turbidity. In the 10 to 15 meters deep seabed, especially in the more rocky caves and coral areas, often seen. The habitat layer rises and falls with the change of water temperature. Spring and summer distribution in the water depth of 10 to 30 meters, the summer season will also appear in the water depth of 2 to 3 meters, fall and winter when the water temperature drops, then swim to the deeper waters of 40 to 80 meters. The temperature range is 15～34℃, and the optimal water temperature is 22～28℃. Wide range of salinity, can survive in the salinity of 10 ‰ above the sea.

2, blackfish

Blackfish have a strong adaptability to water temperature and water quality. When there is a lack of oxygen in the water body, it is able to breathe at the surface of the water with the help of the auxiliary respiratory organs in the upper cavity of the gills. It can survive in water temperatures from 0 to 41℃, and 16 to 30℃ is the optimal temperature for the growth and development of blackfish reproduction. When the water temperature recovers above 8℃ in spring, it is usually active in the middle and upper layers of the water body, and more active in the upper layers of the water body in summer time. When the temperature is lower than 6℃ in fall, the blackfish swims slowly at this time and often lurks in the depths of the water layer, and buries itself in the silt to overwinter when the water temperature is close to 0℃ in winter.

Baidu Encyclopedia-Grouper

Baidu Encyclopedia-Blackfish