Home / Fishes / Tetras, piranhas and pacus / Emperor tetra
No federal permit to keepEmperor tetra
Nematobrycon palmeri
Fishes › Tetras, piranhas and pacus (Characiformes) › Characidae (Tetras)
Nematobrycon palmeri, commonly known as the emperor 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 1.7 in / 4.2 cm).
- Water: Freshwater.
- Temperature: 73–81°F (range recorded for this species).
- pH: 5–8.
- Hardness: 5–19 dGH.
- Layout: An open-water swimmer: needs long, open swimming space with few obstacles.
- Diet: Eats a varied diet: mix quality prepared foods with frozen and live foods. 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 35 × 12 in (roughly 21 US gallons); space needed is rated “large tank”.
- Water: a fairly wide range, from slightly acidic to slightly alkaline, 73–81 °F, pH 5–7.5, 1–12 dGH.
- Behaviour: temperament territorial; a shoaling fish best kept in a group of six or more; suited to a community tank.
- Difficulty: Moderate (Seriously Fish rating).
Short excerpts from the species profile:
- Diet: “Likely to be a micropredator feeding on small insects, worms, crustaceans and other zooplankton in nature.”
- Tankmates: “One of the best tetras for the 'general' community setup.”
- Breeding: “Not a difficult species to breed.”
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 species is found in the Atrato and San Juan river basins in western Colombia. It was first imported in the aquarium trade to the United States in 1960 and has since become well established.
Quoted from the Wikipedia article “Nematobrycon palmeri” (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 5–8, hardness 5–19 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, 73–81 °F.
Native climate (measured)
Native climate (measured)
| Warm-season highs | about 88°F (up to 90°F in the hottest sampled areas) |
| Cool-season lows | about 71°F (down to 66°F in the coldest sampled areas) |
| Average temperature | 75–81°F across sampled records |
| Relative humidity | 81–84% on average (driest month about 80%) |
| Rainfall | about 6292 mm a year, spread fairly evenly |
Measured at 9 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 | Nematobrycon palmeri, commonly known as the emperor tetra, is a species of freshwater ray-finned fish belonging to the family Acestrorhamphidae, the American tetras. This species is found in the Atrato and San Juan river basins in western Colombia. It was first imported in the aquarium trade to the United States in 1960 and has since become well established. It is named in honor of Mervyn George Palmer (1882–1954), an English traveler who collected in Central and South America for the British Museum, and who collected the type specimen. — 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 |
| Wild diet | Nematobrycon palmeri is omnivorous in the wild, consuming worms, crustaceans, and plant material. — Animal Diversity Web |
| Behavior | This fish is very peaceful in temperment - one of the reasons for its popularity in the aquarium trade (Lundie 2000). — Animal Diversity Web |
| Reproduction | Nematobrycom palmeri is dioecious, meaning there are male reproductive organs in one individual and female reproductive organs in another. — Animal Diversity Web |
| Appearance and size | Nematobrycon palmeri has a body that is about 39 mm deep and laterally compressed. — Animal Diversity Web |
| Biology | Feeds on worms and crustaceans. Aquarium keeping: in groups of 5 or more individuals; minimum aquarium size 80 cm. — FishBase |
| Conservation | This species does not have an IUCN threatened status (Torres 2000). — Animal Diversity Web |
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.
Minimum tank footprint
Seriously Fish recommends a tank base of at least 35 × 12 in (about 21 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.
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