Arctoscopus japonicus, the sailfin sandfish or Japanese sandfish, is a species of fish of the Percomorpha (perch-like) clade in the order Trachiniformes, being one of the two genera in the family Trichodontidae, the sandfishes. Known in Japan as hatahata (ハタハタ, 鰰, 鱩, 燭魚), it is a commercially important fish especially for Akita and Yamagata prefectures. Its habitat occurs in sandy-mud bottoms ranging from the Sea of Japan to the Okhotsk Sea. The fish had also been used dried or in fish meal form as fertilizer, and shipped to agricultural areas at one time, into the 20th century.