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Anableps anableps
Fishes › Killifish and livebearers (Cyprinodontiformes) › Anablepidae (Four-eyed fish and livebearers)
Anableps anableps, the largescale four-eyes, is a species of four-eyed fish found in fresh and brackish waters of northern South America and Trinidad.
Care at a glance
Species-specific values
Values researched for this exact species. Where they differ from the group guide below, follow these. Air, surface and water temperatures are listed separately, and each source is kept as published rather than averaged.
| Water temperature | 77–88 °F (25–31 °C) Maintenance recommendations from this source; do not replace with a multisource average. | 265 |
| Water pH | 7.5–9 Maintenance recommendations from this source; do not replace with a multisource average. | 265 |
| Water general hardness | 15–35 dGH Maintenance recommendations from this source; do not replace with a multisource average. | 265 |
| Adult standard length | 260 mm Maximum standard length reported by source; excludes caudal fin, not total body length. | 265 |
| Minimum tank base | length: 150 cm; width: 45 cm Minimum aquarium base recommended by this source, not a tank-volume specification. For a group; a large surface area and shallow water are important. | 265 |
| Minimum social group | 6 fish | 265 |
| Water salinity | Brackish water; do not treat this as a freshwater annual killifish. | 265 |
| Tank layout | Shallow water, broad surface area, exposed resting areas, humid air space and a tightly fitted cover. | 265 |
Species-specific aquarium care
- Tank: At least 24 in long and 12 in front to back for one adult (adults commonly reach about 5.5 in / 14 cm; the largest recorded was 11.8 in).
- Water: Freshwater (tolerates brackish).
- Temperature: 75–82°F (range recorded for this species).
- Layout: Lives on or near the bottom: floor space and hiding places matter more than height.
- Diet: A predator: feed meaty foods sized to its mouth (frozen fish, shrimp, worms); it will eat tankmates that fit in its mouth. FishBase classes it as a carnivore.
Calculated from this species' own FishBase record: tank size from its typical adult length and swimming zone, water values from its recorded ranges. The group guide below fills in general care.
Care guide
Species care notes
- Tank: a base of at least 59 × 18 in (roughly 80 US gallons); space needed is rated “very large tank”.
- Water: hard, alkaline water, 77–88 °F, pH 7.5–9, 15–35 dGH.
- Behaviour: a shoaling fish best kept in a group of six or more; not a community fish.
- Difficulty: Moderate (Seriously Fish rating).
Short excerpts from the species profile:
- Setup: “It's exposed to highly variable salinity levels between 5-30‰ in the wild so water chemistry isn't too much of a concern; for ease of maintenance a specific gravity between 1.005-1.015 is normally recommended.”
- Diet: “In nature it has a diverse, but highly adapted, feeding strategy dependant on environmental conditions.”
- Tankmates: “Best kept in a species-only display and may predate on much smaller fishes but in very large tanks can be combined with peaceful estuarine fishes.”
- Breeding: “Anableps species are viviparous and mating usually presents few problems provided you have a mixed-sex group.”
From the Seriously Fish profile for this species, which has the full habitat, maintenance, diet, behaviour and breeding write-up 167
Four-eyed livebearers
Applies to most species in this group. Habitat: Brackish mangrove margins, feeding at the water surface and flooded shoreline. [sf-anableps-anableps]. Individual species can differ, so compare with the species numbers above and the linked sources.
Housing & setup
- At least 150 × 45 cm floor area for no more than six adults in the cited example; prioritize surface area and provide substantially more for larger groups.
- Shallow water around 15 cm, exposed/sloping resting areas, secure jump-proof cover, humid air space and substantial filtration.
- Brackish specific gravity 1.005–1.015; pH 7.5–9, hardness 15–35 dGH.
Climate & lighting
| Water | 77–87.8°F |
Diet
- Feed twice daily: varied insect/aquatic invertebrate foods plus algae/vegetable components; Spirulina-containing dry food alone is not the suggested staple.
Social life
- At least six conspecifics; species display preferred, since smaller fish can be eaten.
Handling
- Minimize restraint; protect skin with nitrile gloves during necessary direct veterinary handling.
Health watch
- Monitor pregnancy and newborn development; premature births are reported and their causes remain uncertain.
Understanding the animal
About this animal
About this animal
This species grows to a length of 24.5 centimetres (9.6 in) standard length (SL). This fish can occasionally be found in the aquarium trade.
Quoted from the Wikipedia article “Anableps anableps” (CC BY-SA 4.0) 174
In the wild
In the wild
From this species’ own FishBase record (habitat, bottom type, water and breeding data), not its family. Good care copies these conditions.1
| Where it lives | Lives in freshwater and brackish water, in rivers and streams, lakes, estuaries, mangroves. Stays near the bottom. Mainly found in freshwater, sometimes in brackish parts of lagoons and mangrove coastlines. |
| Ground it lives on | Over mud. |
| Water it lives in | Freshwater / brackish water, 75–82 °F (24–28 °C). |
| Climate | Tropical climate. |
| Wild diet | Hunting macrofauna (predator). |
| Behavior to plan for | Breeding: internal live bearers. |
What this means for care
- Keep water within its wild range, 75–82 °F.
- Use a soft, fine bottom; it lives over fine sediment in the wild.
- It tolerates or needs brackish water; check salinity needs before setup.
Native climate (measured)
Native climate (measured)
| Warm-season highs | about 89°F (up to 91°F in the hottest sampled areas) |
| Cool-season lows | about 72°F (down to 70°F in the coldest sampled areas) |
| Average temperature | 78–81°F across sampled records |
| Relative humidity | 79–84% on average (driest month about 77%) |
| Rainfall | about 2168 mm a year |
Measured at 102 wild occurrence records sampled against WorldClim 2.1 climate data (1970–2000 averages). Air conditions in the range are ecological context, not enclosure settings: microhabitats such as burrows, leaf litter or basking rocks can be cooler, warmer or more humid.
From the sources
From the sources
Quoted from the matching sections of reputable sources for this exact species. Specialist databases are used first; Wikipedia (community-edited, CC BY-SA 4.0) only fills gaps. Other sources are short credited quotes.
| Overview | Anableps anableps, the largescale four-eyes, is a species of four-eyed fish found in fresh and brackish waters of northern South America and Trinidad. This species grows to a length of 24.5 cm standard length (SL). This fish can occasionally be found in the aquarium trade. The fish does not actually have four eyes. — Wikipedia (community-edited) |
| Where it lives | Home ranges Population dynamics Growth parameters Max. ages / sizes Length-weight rel. Length-frequencies Mass conversion Recruitment Abundance Life cycle Reproduction Maturity Maturity/Gills rel. — FishBase |
| Reproduction | Length at birth 4.5 5.2 cm TL. — FishBase |
| Appearance and size | Maximum length 30.0 cm tl male/unsexed; maximum published weight 400.00 g. — FishBase |
| Biology | Mainly found in freshwater, sometimes in brackish parts of lagoons and mangrove coastlines. Feeds on insects, other invertebrates and diatoms living on the mud, and small fishes. Can remain on mud bottom exposed to air during low tide. — FishBase |
| History and naming | The name "Anableps" comes from the Greek "ana", meaning "up", and "blepo", meaning "sight" or "glance". This fish was first described in 1758 by the Swedish naturalist Carl Linnaeus in the tenth edition of his Systema Naturae. Linnaeus originally placed the fish in the genus Cobitis, the spiny loaches. — Wikipedia (community-edited) |
Data and studies
The numbers
The numbers
Each bar is what one source reports. Where several sources weigh in, the dashed gold band marks their average.
Typical adult weight
Average adult body mass in each database (FishBase gives the maximum recorded weight).
Adult length
Common length to maximum recorded length. Measured as total length. Fish in home aquariums often stay smaller than wild records.
Water temperature
Range the species tolerates in nature; aim for the middle.
pH
Water hardness
Minimum tank footprint
Seriously Fish recommends a tank base of at least 59 × 18 in (about 80 US gallons).
Veterinary & husbandry research
Veterinary & husbandry research
- The differential optomotor response of the four-eyed fish Anableps anableps Albensi BC et al., Perception 1998
Peer-reviewed papers that mention this species alongside captivity, zoos, veterinary care or aquaculture. Some cover several species or mention it only in passing, so check the abstract. 170
Sources for this sheet
- FishBase (Froese & Pauly, eds.), version 24.07 Peer-reviewed researchThe global scientific database on fishes, maintained by a consortium of research institutions; every value is referenced.
- Seriously Fish species profiles Experienced keeper or breederLong-running aquarium reference written and peer-checked by experienced fishkeepers and ichthyologists; each profile covers habitat, tank size, water, diet, behaviour and breeding.
- Seriously Fish: Anableps anableps Experienced keeper or breederAdded in the 2026 source-checked care-guide review.
- Merck Veterinary Manual: Management of aquarium fish Zoo, university or veterinaryThe Merck Veterinary Manual: a standard veterinary reference written and reviewed by veterinary specialists.
- FishBase: Anableps anableps species summary Zoo, university or veterinaryAdded in the 2026 source-checked care-guide review.
- Wikipedia (species article) Community referenceFree encyclopedia; useful overviews with their own citations. Intro text is quoted under CC BY-SA 4.0.
- PubMed (U.S. National Library of Medicine) Peer-reviewed researchIndex of peer-reviewed veterinary, zoo and husbandry research.
- iNaturalist (captive observations) Community referenceCommunity observation platform run by the California Academy of Sciences and National Geographic; observations marked captive show animals living in homes, zoos and aquariums.