Sepia bathyalis is a species of cuttlefish native to the southwestern Indian Ocean, specifically northwestern and southwestern Madagascar. It lives at a depth of between 300 and 500 m.

Sepia bathyalis grows to a mantle length of 80 mm.

The type specimen was collected near Madagascar (22°19′S 43°06′E to 22°23′S 43°06′E). It is deposited at the Zoological Museum in Moscow.

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