Killifishes and Live-Bearers: Cyprinodontiformes

Physical characteristics: Largescale foureyes have large, bulging, froglike eyes set far forward and divided by a black band into upper and lower portions that see above and below the waterline. These fish grow to 12 inches (30 centimeters). They are long and narrow and have a flat head. The dorsal (DOOR-suhl) fin, the one along the midline of the back, is far toward the rear of the body. Three to five blue to purple lines run along the sides of the body. The back is brownish with a whitish line that divides into a Y at the gill cover, each arm ending at an eye.

Largescale foureyes see well both above and below the waterline. Because they swim with the upper half of their eyes above the water, they bob their heads up and down to keep their eyes wet. (Illustration by Emily Damstra. Reproduced by permission.)

Geographic range: Largescale foureyes live along the northeast coast of South America.

Habitat: Largescale foureyes live in rivers, streams, and estuaries near beaches.

Diet: Largescale foureyes jump out of the water at low tides to gulp down mud, which is rich in algae, tiny animals, and worms. These fish leap from the water to catch low-flying insects. They also eat small fishes.

Behavior and reproduction: Largescale foureyes see well both above and below the waterline. Because they swim with the upper half of their eyes above the water, they bob their heads up and down to keep their eyes wet. These fish ride breaking waves near sandy beaches, sometimes being tossed onto the beach by the waves. They just jump back into the water. These fish form schools of as many as hundreds of fish.

Largescale foureyes are live-bearers that use internal fertilization (FUR-teh-lih-zay-shun), meaning egg and sperm unite inside the female's body. About twenty weeks after fertilization, ten to twenty young are born. These young fish are as large as 2 inches (5 centimeters) at birth. This size is remarkable because the parents may be only 3½ inches (9 centimeters) long.

Largescale foureyes and people: Largescale foureyes are eaten. To a limited extent, they are sold for aquariums.

Conservation status: Largescale foureyes are not threatened or endangered. ∎