The arrow goby (Clevelandia ios) is a species of goby native to marine and brackish waters of the Pacific coast of North America from British Columbia to Baja California. This species grows to a length of 6.4 centimetres (2.5 in) SL, though most do not exceed 4.2 centimetres (1.7 in) TL. This fish can also be found displayed in public aquaria. This species is the only known member of its genus.