Home / Fishes / Tetras, piranhas and pacus / Glass tetra
No federal permit to keepGlass tetra
Moenkhausia oligolepis
Fishes › Tetras, piranhas and pacus (Characiformes) › Characidae (Tetras)
Moenkhausia oligolepis, commonly known as the redeye tetra and the glass tetra, is a species of ray-finned fish in the family Acestrorhamphidae.
Intro from Wikipedia (CC BY-SA 4.0)
Care at a glance
Species-specific aquarium care
- Tank: At least 24 in long and 12 in front to back for one adult (adults commonly reach about 3.9 in / 10 cm).
- Water: Freshwater.
- Layout: Uses both the bottom and open water: give open swimming space plus cover near the substrate.
- 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 24 × 15 in (roughly 18 US gallons); space needed is rated “modest tank”.
- Water: a fairly wide range, from slightly acidic to slightly alkaline, 75–82 °F, pH 5.5–7.2, 1–12 dGH.
- Behaviour: temperament peaceful; a shoaling fish best kept in a group of six or more.
- Difficulty: Easy (Seriously Fish rating).
Short excerpts from the species profile:
- Setup: “A biotope setup would be very simple to arrange.”
- Tankmates: “It's a very peaceful species that won't compete well with very boisterous or much larger tankmates.”
- Breeding: “Can be bred in a similar way to other species in the genus.”
From the Seriously Fish profile for this species, which has the full habitat, maintenance, diet, behaviour and breeding write-up 167
Tetras
Applies to most species in this group. Habitat: The covered characids include South American river and tributary fishes, from vegetation-shaded bloodfin habitats to sandy flowing rivers occupied by Exodon. [fg156-bloodfin, fg156-exodon]. Individual species can differ, so compare with the species numbers above and the linked sources.
Housing & setup
- For glass bloodfins, use at least 60 × 38 × 30 cm (24 × 15 × 12 in), retaining open upper-water swimming space.
- Provide planted margins and floating vegetation for bloodfins; fit a tight lid for Aphyocharax anisitsi.
- For bucktooth tetras use at least 120 × 45 × 45 cm (48 × 18 × 18 in), efficient filtration and planted refuges from bullying.
- For glass bloodfins maintain pH 6.0–7.5; for Exodon, pH 5.5–7.5.
Climate & lighting
| Water | 73.4–80.6°F |
Diet
- Small dried foods for glass and ordinary bloodfins.
- Daphnia, Cyclops and bloodworms for glass bloodfins.
- For Exodon, chopped prawns, mussels, earthworms and fish rather than live feeder fish.
Social life
- Glass bloodfins need 6–8 or more; ordinary bloodfins at least six. Exodon requires a species aquarium and at least 12 introduced together; small groups can kill one another.
Health watch
- Freshwater ich (white spot disease), a general aquarium risk.
- Bacterial infections associated with stress and poor water quality.
- Fin and scale damage from aggression, especially Exodon.
Understanding the animal
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, in rivers and streams. Uses both the bottom and open water. A gregarious species which prefers the counter current zones of small creeks. Omnivorous. It is very prolific and reproduction in the aquarium is very easy to carry out. |
| Water it lives in | Freshwater. |
| Climate | Tropical climate. |
| Wild diet | Hunting macrofauna (predator). |
| Behavior to plan for | Breeding: open water/substratum egg scatterers. |
Native climate (measured)
Native climate (measured)
| Warm-season highs | about 91°F (up to 94°F in the hottest sampled areas) |
| Cool-season lows | about 68°F (down to 58°F in the coldest sampled areas) |
| Average temperature | 76–80°F across sampled records |
| Relative humidity | 76–83% on average (driest month about 72%) |
| Rainfall | about 2132 mm a year |
Measured at 921 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.
| 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 |
| Biology | A gregarious species which prefers the counter current zones of small creeks. It is very prolific and reproduction in the aquarium is very easy to carry out. — FishBase |
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.
Adult length
Maximum recorded length. Measured as standard length (snout to the base of the tail, not counting the tail fin). Fish in home aquariums often stay smaller than wild records.
Water temperature
Range the species tolerates; aim for the middle.
pH
Water hardness
Minimum tank footprint
Seriously Fish recommends a tank base of at least 24 × 15 in (about 18 US gallons).
Veterinary & husbandry research
Veterinary & husbandry research
- Embryonic development of the fire-eye-tetra Moenkhausia oligolepis (Characiformes: Characidae) Dos Santos RS et al., Zygote (Cambridge, England) 2021
- Seminal characterization of the Amazonian fire-eye tetra Moenkhausia oligolepis (Günther, 1864) Rodrigues J et al., Zygote (Cambridge, England) 2020
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: Prionobrama filigera Experienced keeper or breederAdded in the 2026 source-checked care-guide review.
- Seriously Fish: Exodon paradoxus Experienced keeper or breederAdded in the 2026 source-checked care-guide review.
- Seriously Fish: Aphyocharax anisitsi Experienced keeper or breederAdded in the 2026 source-checked care-guide review.
- Merck Veterinary Manual: Disorders and Diseases of Fish 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.
More tetras
Axelrodia stigmatias
Axelrodia stigmatias
Aquarium hobby
Black neon tetra
Hyphessobrycon herbertaxelrodi
Aquarium hobby
Black phantom tetra
Hyphessobrycon megalopterus
Aquarium hobby
Black tetra
Gymnocorymbus ternetzi
Aquarium hobby
Blackline penguinfish
Thayeria boehlkei
Aquarium hobby
Bleeding heart tetra
Hyphessobrycon erythrostigma
Aquarium hobby