Shishamo (柳葉魚, literally "Willow Leaf Fish"), or Spirinchus lanceolatus, is a saltwater fish (smelt) about 15 centimeters in length. It is slim and resembles a willow leaf; the Japanese name, shishamo, is derived from the Ainu name for the same fish, susam, which is supposed to be derived from a compound of Ainu susu "willow" + ham "leaf", hence its name in Chinese characters (jukujikun, where the characters have no phonetic relation to the word). It is generally dark on the back with a silver-white underside.