Okenia mija is a species of sea slug, specifically a dorid nudibranch, a marine gastropod mollusc in the family Goniodorididae.
This species was described from south-eastern Australia. It is known from New South Wales, Victoria and Tasmania.[1]
This Okenia has a narrow body and seven pairs of short lateral papillae. There are many papillae on the back, between the rhinophores and the gills and some on the sides of the body. The body is translucent and has some small spots of brown and white pigment. It is similar in shape and arrangement of the papillae to Okenia angelensis, Okenia zoobotryon, Okenia harastii and Okenia distincta.
The diet of this species is a bryozoan, Amathia wilsoni.