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No federal permit to keepGlowlight tetra
Hemigrammus erythrozonus
Fishes › Tetras, piranhas and pacus (Characiformes) › Characidae (Tetras)
Hemigrammus erythrozonus, the glowlight tetra, is a species of freshwater ray-finned fish belonging to the family Acestrorhamphidae, the American characins.
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 1.3 in / 3.3 cm).
- Water: Freshwater.
- Temperature: 75–82°F (range recorded for this species).
- pH: 6–8.
- Hardness: 5–12 dGH.
- Layout: Uses both the bottom and open water: give open swimming space plus cover near the substrate.
- Diet: Eats a varied diet: mix quality prepared foods with frozen and live foods. FishBase classes it as a omnivore.
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 5.5–7.5, 2–15 dGH.
- Behaviour: a shoaling fish best kept in a group of six or more.
- Difficulty: Moderate (Seriously Fish rating).
Short excerpts from the species profile:
- Setup: “As it's commercially bred in such huge numbers, it is adaptable and will do well in most tanks.”
- Tankmates: “One of the best tetras for the 'general' community setup.”
- Breeding: “Quite easily bred, although you'll need to set up a separate tank in which to do so if you want to raise any numbers of fry.”
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 found in the Essequibo River and the Courantyne River in Guyana and Suriname. It is silver in colour and a bright iridescent orange to red stripe extends from the snout to the base of its tail, the front of the dorsal fin being the same color as the stripe.
Quoted from the Wikipedia article “Hemigrammus erythrozonus” (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. Uses both the bottom and open water. Feeds on worms, small crustaceans and plants. |
| Water it lives in | Freshwater, 75–82 °F (24–28 °C), pH 6–8, hardness 5–12 dH. |
| Climate | Tropical climate. |
| Behavior to plan for | Breeding: open water/substratum egg scatterers. |
What this means for care
- Keep water within its wild range, 75–82 °F.
Native climate (measured)
Native climate (measured)
| Warm-season highs | about 89°F (up to 93°F in the hottest sampled areas) |
| Cool-season lows | about 70°F (down to 67°F in the coldest sampled areas) |
| Average temperature | 77–80°F across sampled records |
| Relative humidity | 78–82% on average (driest month about 75%) |
| Rainfall | about 2127 mm a year |
Measured at 24 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 | Hemigrammus erythrozonus, the glowlight tetra, is a species of freshwater ray-finned fish belonging to the family Acestrorhamphidae, the American characins. This fish is found in the Essequibo River and the Courantyne River in Guyana and Suriname. It is silver in colour and a bright iridescent orange to red stripe extends from the snout to the base of its tail, the front of the dorsal fin being the same color as the stripe. Other fins are silver to transparent. — 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 | H. erythrozonus breeds similarly to most egg-scattering small fish. It been bred in captivity with a moderate level of difficulty. Breeding tank set-up: A small 40l all-glass tank with soft water (hardness up to 8°dGH and carbonate hardness not higher than 2°dCH). — Wikipedia (community-edited) |
| Biology | Feeds on worms, small crustaceans and plants. Maximum length questionable. Maximum length reported to reach 4 cm TL. — 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 total length. Fish in home aquariums often stay smaller than wild records.
Water temperature
Range the species tolerates in nature; aim for the middle.
Minimum tank footprint
Seriously Fish recommends a tank base of at least 24 × 15 in (about 18 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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