The differences between the opium fish and the saucerfish are: different physical manifestations, different distribution areas, and different nutritional values.

1, the body performance is different

Opium fish body is very long, slightly flattened, the abdomen is round. The first half of the head is elongated, slightly tubular, and the end of the muzzle is flattened like a duck's beak. The mouth is superior, the lower jaw is inclined upward and longer than the upper jaw, and the end of the maxilla reaches below the anterior margin of the eye. Eyes equal in size, closer to end of muzzle, protruding to both sides of face, cheeks very broad, postocular head length 2 to 2.5 times muzzle length.

Dark gray on the back, silvery white on the belly and lower part of the sides, the pectoral fins light red, the dorsal and caudal fins gray, the ventral and anal fins gray, and the posterior margin of the caudal fins black, with a slight black longitudinal stripe above the lateral line. It is a large and ferocious fish in rivers.

Opisthobranchus:

Saucerfish:

Saucerfish have a disc-shaped body, with extremely long dorsal and anal fin bases, which join the caudal fin almost posteriorly. The body is laterally compressed, elongated oval, ovoid or long tongue-shaped, with a maximum length of up to 5 M. The adult body is asymmetrical from side to side. Both eyes are located on the left or right side of the head. The mouth is slightly protruding. The fins are generally without fin spines. The dorsal and anal fins are basally long and may or may not be attached to the caudal fin. It is widely distributed in warm and hot waters of all oceans, feeding mainly on benthic invertebrates and fish.

2, the distribution area is different

Opisthoceros is native to the northern waters of the Atlantic Ocean, widely distributed in the tropical or temperate oceans, so the world's temperate zones are introduced to the sea, China is mainly distributed in the Yellow Sea and the Bohai Sea.

There are more than 200 species of butterflyfish, and most of them are found in the Pacific Ocean, Indian Ocean, coral reefs or shallow waters around the world. It is mainly concentrated in the waters around Indonesia, with more than 60 species. In the South China Sea, including Taiwan Island, Hainan Island, Dongsha Islands, Xisha Islands and Nansha Islands, has been found to have as many as 48 species of butterflyfish.

3, nutritional value is different

Opium fish meat is tender and white, Chinese medicine, opium fish taste sweet, sexuality, non-toxic; can replenish the deficiency and benefit the gas. Taste fresh and fat, replenish the deficiency and benefit the qi, but should not be eaten more than one, there is the effect of moving the qi, the general population can be eaten.

Flounder is very low in fat, only 139 calories per 140 grams of flounder meat, so it is very suitable for dieters. Flounder is rich in phosphorus, selenium, iodine, vitamin B and other nutrients, which are very effective for human skin and hair.

Baidu Encyclopedia - Opium Fish

Baidu Encyclopedia - Discus Fish

People's Daily Online - Experts' Inventory: Seafoods with the Most Nutritional Value