Sepia tanybracheia is a species of cuttlefish native to the southeastern Indian Ocean. It is known only from the type locality. S. tanybracheia lives at depths of 200 to 205 m. Males grow to a mantle length of 51 mm. The type specimen was collected off Western Australia (12°36′S 123°45′E / 12.600°S 123.750°E) and is deposited at the Museum of Victoria in Melbourne.