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Finescale Four-eyed Fish

Anableps microlepis

An extraordinary brackish water fish famous for its dual-vision eyes, which allow it to search for food and watch for predators above and below the surface.

Taxonomy

Class:Actinopteri

Order:Cyprinodontiformes

Family:Anablepidae

Genus:Anableps

Species:Anableps microlepis

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Water Temperature

24 - 28 °C

pH Value

7.5 - 8.5

Water type

Freshwater / Brackish

Tank level

Surface

Adult size

30 cm

Minimum tank volume

>= 350 L

Minimum group

>= 6

4 - 15 dGH

2 - 7 dKH

TDS

80 - 295 ppm

Conductivity

125 - 461 uS/cm

Species description

Geographical Origin and Habitat: Anableps microlepis is found along the northern coast of South America, from the Orinoco River delta in Venezuela to the Amazon River mouth in Brazil. It inhabits shallow brackish waters, mangrove swamps, muddy estuaries, and tidal flats where it stays near the shoreline.

Taxonomy and Morphology: Belonging to the family Anablepidae, this species is named for its horizontal eye split, creating two pupils in each eye for simultaneous air and water vision. It has an elongated, cylindrical body covered in very small scales and can reach a length of 12 inches (30 cm).

Social Behavior: Highly social, schooling fish that spend their entire lives swimming right at the water surface. They are active during the day and are easily startled, often leaping out of the water to escape perceived threats or predators.

Coloration and Sexual Dimorphism: Body coloration is olive-brown to silvery-gray with a pale belly. They are livebearers exhibiting unilateral specialized reproduction: males have a modified anal fin called a gonopodium that bends either to the left or right, mating only with females whose genital openings match.

Care, breeding and tankmates

Aquarium Setup: Requires a wide tank with a large footprint rather than depth (at least 120 cm length and 400 liters). A tight-fitting lid is absolutely critical as they are exceptional jumpers. Decorate with a sandy substrate and smooth roots, leaving the surface completely unobstructed.

Diet and Feeding: Surface-oriented carnivore. Feed live and frozen foods that float, such as crickets, fruit flies, bloodworms, brine shrimp, and floating pellet foods. They rarely consume food once it has fallen to the bottom.

Water Quality: Best kept in brackish water conditions with a specific gravity between 1.005 and 1.012. Maintain temperatures at 24-28°C (75-82°F), pH 7.5-8.5, and hard water. Good biological filtration and regular water changes are essential to prevent accumulation of wastes.

Compatibility and Cohabitation: Peaceful but will consume any fish small enough to fit in their mouths. Best housed in a species-only group or with large brackish tankmates like archerfish (Toxotes), mudskippers, and silver monos (Monodactylus).

Aquarium Breeding: Viviparous (gives birth to live young). Breeding requires matched pairs of compatible lateral orientation. After a gestation period of around 2 months, the female releases 10-30 large, fully developed fry (about 4 cm long) that require immediate feeding.

Risks and Diseases: Highly susceptible to bacterial skin infections and columnaris if kept in freshwater long-term. Physical damage to their protruding eyes from rough decorations or jumping accidents can easily lead to blindness or fatal infections.

Geographic Origin and Distribution

Anableps microlepis is found along the northern coast of South America, from the Orinoco River delta in Venezuela to the Amazon River mouth in Brazil. It inhabits shallow brackish waters, mangrove swamps, muddy estuaries, and tidal flats where it stays near the shoreline.

Origin

Amazon, Orinoco, and Guianas

Fish profile

Temperament: Active
Diet: Carnivore
Sex ratio: Group
Feeding frequency: Twice daily
Bioload: This is a large, messy fish with a high bioload. They eat heavily and excrete a lot of waste. Powerful filtration and frequent water changes are completely necessary.
Flow: Strong
Jump risk: Yes
Reproduction: Livebearer
Compatibility & tankmates: Peaceful
Tank level: Top

FishBase

Window to the official scientific data of the species

Data synced on: 06/15/2026

Scientific Parameters & Models

Trophic level: 2.8 ± 0.3 se
Resilience: Low (4.5 - 14 years)
Phylogenetic uniqueness (PD50): 0.625
Bayesian Length-Weight: a = 0.00537, b = 3.15

Image gallery

Licensed images linked to the species or, when marked, to the closest representative taxon.

Related species

Recommendations grouped by close relatives, companion choices, and similar care.

Variants and close relatives

Same atlas type, nearby scientific identity, genus, or family.

Pacific four-eyed fish

Anableps dowei

Species description

Care, breeding and tankmates