Latin name

Anguilla japonica

Other names

Nihon unagi  

Identification

Vertebrae: 114-118. Head length 11.2-11.9% (11.6%) of body length (according to Ege, females 13, males 12-13%). Maxillary length from 3.7 to 4.3% of head length.

Japanese scientists have confirmed the eel's ability to fluoresce. The Japanese eel is the first vertebrate to do so. Scientists have identified protein structures responsible for the absorption and re-emission of light, the chromophore is bilirubin. According to the researchers, the concentration of the protein in young eels is sufficient to make their bodies glow green in the dark when illuminated by a blue lamp.

Features of fish fins

The distance from the beginning of the dorsal fin to the anus varies from 9.0 to 13.5% (mean 10.9%) of the total body length (by Ege, mean 9.2%). The length of the pectoral fin varies from 2.2 to 3.7% of the head length.

Fish colouring

Colour is monotonous, uniformly dark brown on the back and lighter on the belly. There are no large patches on the body. 

Distribution

Widespread off the coast of Japan and the East China Sea, off the coasts of Taiwan, Korea, China and the northern Philippines.

Habitat

Marine, freshwater, brackish, bottom-dwelling, catadromous, subtropical species. Lives on the bottom, at depths of up to 400m. 

Size

The body reaches a length of about 40 cm, with a maximum length of 1 m. Maximum published weight: 1.9 kg. 

Behavior

Can live in both fresh and salt water. Can move on land at night. A transient species. Spawns in the deep waters of the Pacific Ocean. Juvenile eels enter rivers in schools from February to May and ascend to headwaters and mountain lakes. After several years in freshwater and the onset of sexual maturity, the eels roll down the river and go to sea from August to October. 

Food and feeding habits

It feeds on crustaceans, insects and fish.

Reproduction

Spawning grounds of this species have been found in the western Mariana Islands. Spawns in the sea. Juveniles migrate to rivers in schools and develop and grow in freshwater. 

Fishing

An important freshwater commercial fish, farmed in large numbers in ponds.

Relationship with a person

It is used in Japanese cuisine, where it is considered the most expensive fish. It is bred in special Japanese farms in the sea. It is also used in traditional Chinese medicine.