The fatspine spurdog, Squalus crassispinus, is a dogfish of the family Squalidae, found on the continental shelf off the northern coast of Western Australia, at depths of 180 to 200 metres (590 to 660 ft). The length of the longest male specimen measured is 56 centimetres (22 in). The fatspine spurdog is a rare, small and slender dogfish with a broad head and short snout. There is a broad, small medial barbel on the anterior nasal flaps. The pectoral fin has a shallowly concave posterior margin. The first dorsal fin is moderately high, and both dorsal fin spines are very stout.