1. The turbot is a genus of flatfish in the family Turbot, commonly known as the European flounder, called turbot in China, in natural waters, the adult fish can grow up to 75 centimeters, the body is even sideways flat, long oval, ovoid or long tongue-shaped, juvenile eyes on both sides of the body, the body of the adult fish is not symmetrical, one eye gradually to the left or right, both eyes are located in the left side of the head or on the right side of the mouth is slightly protruding, fins are generally not fin spines, the dorsal fin and anal fin base is long, and the caudal fin is connected or not connected, both eyes are the same side of the body toward the top. The dorsal and anal fins are basally long and connected or not to the caudal fin, both eyes are on the same side of the body facing upwards, the color of this side matches the surroundings well, the downward-facing side of the body is white, and the surface of the body has very fine scales.

2. The fish is also called high-eye flounder, the body is ovoid, laterally compressed, with a narrow and long caudal peduncle, both eyes are located on the right side of the head, and the upper eye is located on the center line of the head's periphery, the mouth is large, anteriorly positioned, symmetrical left and right, the eyed side is mostly covered with weak pectinate scales, intermittently intermixed with rounded scales, the eyeless side is covered with rounded scales, and the lateral line is almost straight, the dorsal fin starts from the eyeless side, and the pectoral fin on the eyed side is longer, and the caudal fin is truncated, and it's generally 20 cm long and weighs 200 grams or so. The caudal fin is truncated and is usually about 20 centimeters long and weighs about 200 grams.

3. Opium fish:

According to the classification rule of left flounder and right plaice, opium fish is a kind of plaice, and it is wrong to say that opium fish is an alias of flounder. The scientific name of the opossum is Greenland flounder.