Anableps anableps


    Dubbed “The Four-Eyed Fish,” Anableps anableps are a uniquely adapted species whose pupils are divided in 2 parts horizontally. This distinctive feature allows Four-eyed fish the ability to see clearly above and below the water surface at the same time. The implications of such an adaptation provide extra protection from spotting predators, as well as a leg-up on spotting food on or above the surface.

Quick stats:

Listed tank sizes are the minimum
Size: Up to 12in (30cm)
Tank: Minimum of 40 gallon long for school
Strata: Will spend most of all their time at the surface.
Note: Brackish water required and should have a 2.5-3% addition of salt. This can be accomplished by adding 19-23 TSP. of salt/10 gallons (25-30 g/10 L)
PH: PH recommendation 7.0 – 8.5
Hardness: Medium hardness, 8 to 25° dGH
Temperature: 75°F to 82°F (24°-28° C)

Brackish water required and should have a 2.5-3% addition of salt. This can be accomplished by adding 19-23 TSP. of salt/10 gallons (25-30 g/10 L)Classification:

Order: Cyprinodontiformes
Family: Anablepidae
Genera: Anableps
Species: anableps

Common name:

Four-Eyed Fish

South / Central America:: 

    Venezuela to Brazil, in brackish river mouths.

General Body Form:With a long, slender body shape, the Four-eyed fish is not very remarkable until you see their eyes looking at you both above and below the tank surface. They are adapted for “asymmetrical breeding” with right-handed and left-handed males and females needing to match up on their counterparts for mating. Despite its common name, there are only two eyes on this fish. The eyes are however divided into two separate sections each containing a pupil, iris, and cornea, taking light into a divided retina but through a single lens.

Coloration:With few markings and a sandy brown color the Four-eyed fish blends in with its river mouth surroundings, but does not display any bold or vibrant colors as with other tropical fish.

Maintenance:Four-eyed fish are relatively low-maintenance fish, with their very adaptive pH range requirements, so long as it is in a brackish tank. And other than its size it can easily be kept in a school of 6 or more, or a community of large docile brackish fish.

Diet:Being carnivorous fish, they should be fed freeze-dried creatures, small live insects, flake food, as well as frozen brine shrimp and bloodworms. Be warned that they may lose interest in any food that sinks to the bottom or remains motionless, as they like to strike at live prey at the surface of the water.


Biotope:The brackish river mouths of Central America, from Venezuela to Brazil in South America. Plants and decorations are not of much importance to the Four-eyed fish as they will tread along the surface almost entirely. They should be kept in schools of at least 6, or in a community with Archer Fish, Mudskippers or Mollies for example.

Breeding:If kept in a large brackish tank, with large amounts of surface area, Four-Eyed Fish will rather easily breed the same as most other livebearers. Male and females are structured to be mirrored opposites, and lean their sexual organs in a particular direction. The directions vary from fish to fish, so a right-handed male would have to find a left-handed female. They fertilize eggs internally and fry are not born until they are about 1.8in (4.5cm). The ratio of right to left-handedness is about 60:40 in males who tend to be right-handed more often. The same proportion is generally the opposite for females at 40:60.

This profile was written by Chris an active contributor to the site.

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