Pagetopsis macropterus species of marine ray-finned fish belonging to the family Channichthyidae, the crocodile icefishes.

It has a large mouth with the maxilla reaching a level with the front third of the eye and this has two rows of conical teeth in each jaw.

[5] Pagetopsis macropterus has a circum-Antarctic distribution on the continental shelf and the South Shetland Islands.

[1] The defense posture, noted in a study in 1969, is opening the mouth wide, expanding the corner of the mouth and the opercula, erecting the dorsal fin, holding the flared pectoral fins at a right angle towards the body, and bending the body into a semicircle.

The same study suggested that this behavior was developed to deter predators such as the Weddell seal (which preys heavily on this species).