This fish's eyes are split in two so it can watch above and below the waterline at once

Anableps, the "four-eyed fish" of Central and South American rivers, swims with its eyes half-submerged, each one divided by a band of tissue into two separate pupils: one focused on the air above the surface, one on the water below. It effectively watches for airborne predators and prey underwater at the same time, with genuinely different optics serving each half.

— Joseph S. Nelson, Terry C. Grande, and Mark V. H. Wilson, Fishes of the World — 5th edition, Wiley, 2016
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