Mottled eels, the family snake eels, are freshwater fish and big, about 2m long.
The color of body is yellow brown or dark blue and abdomen is light color.
These fish are similar to snake eels, because these have dark-brown-cloudlike figures and small spots on body and fins, it's easy to distinguish each other.
After living in freshwater for 5-8years, they spawn in a deep ocean and then come back to freshwater.
These fish are tropical species and live in the eastern part of Africa, South Pacific, Southeast Asia, and China including Japan and Korea.
Korea as well as Nakasaki of Japan is the northern most habitats in which these can live.In habitat of giant mottled eel in Jeju, there are less insect, small fishes, which are the food of mottled eels because of the water pollution and environment contamination by sightseers and development.
This prevents mottled eels from moving to Cheonjiyeon Lake.
Since marbled eels are rare, regardless of the breeding place, the species itself is designated and proteced as a natural monument.