Hirundichthys is a genus of flying fish. Body elongate, moderately thick, flattened ventrally. Pectoral branch of lateral line absent. Upper jaw not protrusible. Dorsal fin with less or equal (rarely with one more) rays than anal fin; dorsal fin low, anterior rays the longest, pectoral fins strikingly long, reaching to or almost to caudal fin base; pelvic fins long, reaching beyond anal fin origin, their insertion closer to anal fin origin than to pectoral fin insertion.