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No federal permit to keepRainbow tetra
Nematobrycon lacortei
Fishes › Tetras, piranhas and pacus (Characiformes) › Characidae (Tetras)
Nematobrycon lacortei, the rainbow tetra, is a species of freshwater ray-finned fish belonging to the family Acestrorhamphidae, the American tetras.
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 1.4 in / 3.6 cm).
- Water: Freshwater.
- Temperature: 73–81°F (range recorded for this species).
- pH: 5.6–7.2.
- Hardness: 0–12 dGH.
- Layout: An open-water swimmer: needs long, open swimming space with few obstacles.
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 47 × 12 in (roughly 29 US gallons); space needed is rated “large tank”.
- Water: a fairly wide range, from slightly acidic to slightly alkaline, 68–82 °F, pH 5–7.2, 1–10 dGH.
- Behaviour: temperament peaceful; a shoaling fish best kept in a group of six or more; suited to a community tank.
- Difficulty: Easy (Seriously Fish rating).
Short excerpts from the species profile:
- Setup: “Choice of décor is not especially critical, although this species tends to show better colouration when maintained in a well-furnished aquarium with live plants.”
- Diet: “Probably an opportunistic omnivore by nature.”
- Tankmates: “This species is relatively peaceful making it an ideal resident of the well-researched community aquarium, although adult males are territorial and aggressive to an extent, and this behaviour may sometimes extend to similarly-shaped species.”
- Breeding: “Said to breed in a similar way to its congener N.”
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
About this animal
About this animal
This fish is a Colombian endemic with its range restricted to the San Juan and Calima river basins. The rainbow tetra has a maximum standard length of 3.6 cm (1.4 in).
Quoted from the Wikipedia article “Nematobrycon lacortei” (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. |
| Water it lives in | Freshwater, 73–81 °F (23–27 °C), pH 5.6–7.2, hardness 12 dH. |
| Climate | Tropical climate. |
What this means for care
- Keep water within its wild range, 73–81 °F.
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 | Nematobrycon lacortei, the rainbow tetra, is a species of freshwater ray-finned fish belonging to the family Acestrorhamphidae, the American tetras. This fish is a Colombian endemic with its range restricted to the San Juan and Calima river basins. The rainbow tetra has a maximum standard length of 3.6 cm. — 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 |
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 in nature; aim for the middle.
Water hardness
Minimum tank footprint
Seriously Fish recommends a tank base of at least 47 × 12 in (about 29 US gallons).
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.
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