Anguillidae

Japanese eel

Anguilla japonica

Crossing land by night between neighboring rivers

• Brown
• Green
• Yellow
• Cross-climate
• Temperate
• Tropical
• Estuary
• Globally widespread
• Freshwater fish
• Anguilliform
• Large
• Tropical fish

Undertaking one of the most remarkable transoceanic spawning odysseys in the Pacific basin, the Japanese eel is an iconic catadromous teleost inhabiting the freshwater drainages of East Asia. Its supple, cylindrical, snake-like body is cloaked in a protective layer of slippery mucus, lacking pelvic fins and featuring continuous dorsal, caudal, and anal fins that merge seamlessly into a single swimming ribbon. In its continental river feeding phase (yellow eel), it displays an olive-brown to slate-grey back with a pale yellowish-white belly, before transforming upon sexual maturity into a silver eel with metallic bronze dorsal pigmentation, shining silver flanks, and enlarged eyes adapted for the deep ocean. Native to river systems across Japan, Korea, China, Taiwan, and Vietnam, maturing adults migrate thousands of nautical miles southeast into the Philippine Sea to spawn in oceanic trenches near the Mariana Ridge. Transparent leaf-shaped leptocephalus larvae drift northward on the Kuroshio Current, metamorphosing into glass eels before ascending home rivers. Nocturnal carnivores feed on crustaceans and small fishes. Maximum total length attains one hundred and fifty centimetres.

Sources: FishBase & IUCN — Japanese Eel, Anguilla japonica