Sepia braggi, the slender cuttlefish, is a species of cuttlefish native to the Australian waters. It is found in coastal waters on the Continental Shelf at depths between 30 and 86 m. Females of the species are larger than males. They grow to a mantle length of 80 mm and 49 mm, respectively. The type specimen was collected in South Australia and was described by Sir Joseph Cooke Verco in 1907.