Largescale four-eyed fish

Anableps anableps

FreshwaterBrackishFish

Care at a glance

Temperature: 77–88°F (25–31°C)
pH: 7.0–8.0
Adult size: 11.8 in (30 cm)
Minimum tank: 70 gal (265 L)
Temperament: Mostly peaceful
Social behavior: Schooling
Swim level: Top
Difficulty: Difficult
Breeding: No record
Rarity: Very rare
Origin: Brazil, Venezuela, The Guianas
Family: Anablepidae

Overview

This is a surface-living, schooling fish that is best kept in a group of its own kind. It can be aggressive and is tricky to keep, so it is not a beginner fish. Keep brackish water, warm temps in the high 20s C, and a tight lid, since it spends its life at the top. Feed floating and surface foods like live or frozen insects, bloodworms, and mosquito larvae.

In the wild

The largescale four-eyed fish lives at the surface of brackish and fresh waters in Brazil, Venezuela, and the Guianas, especially estuaries, mangroves, and muddy coastal rivers. It cruises the very top, eyes poking above the waterline. That means a wide, shallow tank matters far more than a deep one, with brackish water and open surface space. Adults hit 30 cm, so plan on a large footprint, around 265 liters or more.

Good to know

Anableps anableps is in the family Anablepidae and reaches about 30 cm. Its eyes are split horizontally into upper and lower halves, each with its own pupil, so it sees above and below water at the same time. It is a livebearer with an unusual one-sided mating arrangement. The species is widespread and listed as Least Concern.

Did you know

Because it rides right at the waterline, its eyes can dry out, so it dips its head under every so often to wet them. The upper half of each eye is tuned for air vision and the lower half for water, which effectively gives it two different focal setups in one eyeball.