Seeing Double? The Curiously Strange Four-Eyed Fish

How can a four-eyed fish have only two eyes?

While commonly named the four-eyed fish, this species of fish actually only has two eyes. However, their eyes have developed in a way that actually enables them to see above and below the water’s surface at the same time. Unlike most round eye pupils, this fish species has hourglass shaped pupils. This adaptation helps them avoid both aerial and aquatic predators.

Strangely enough, this interesting adaptation is not the only unique feature of this fish species. The four-eyed fish also has extremely mammalian reproductive characteristics. The species is a live birth, placental and internal fertilization species just like mammals.

Here at the Zoo, we have been successful in rearing these juvenile four-eyed fish. We currently have five young four eyes growing up in our nursery tank. Although fully formed when born, they are miniature versions of the parent fish. They are extremely cute at this stage when they are just learning about their surroundings. So they can relax from swimming occasionally, we created resting areas at the surface of the water made from rock and wood. When first born, they actually act like frogs, resting at the water and land’s edge.

Unfortunately, the new babies are not exactly the best eaters. We offer numerous food options for them, including wingless fruit flies, pinhead crickets and a high-quality fish flake food. In the first few months, the food items must float on the surface of the water for them to recognize it as their food.

When visiting the Zoo, please make time to visit the Aquaticus building and check out the four-eyed fish, one of the more distinctive fish in the world.

--Erik Kalen, Aquarium assistant curator

Photo: Joel Sartore, National Geographic 

Purchase Joel Sartore's Photo Ark book at the Zoo's Safari Gift Shop to find more photos of the Oklahoma City Zoo's animals. 

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