Emperor tetra (Nematobrycon palmeri) care guide

Group
Freshwater fish
Other names
Emperor, Black emperor tetra (colour form)
Family
Acestrorhamphidae (American tetras; formerly Characidae)
Origin
Endemic to the San Juan and Atrato river basins on the Pacific side of western Colombia.
Water
freshwater
Maximum size
4.2 cm
Temperature
23–27°C
pH
5–7.5
Hardness
Soft to medium, 1–12 dGH
Minimum tank
80 litres
Care level
beginner
Temperament
peaceful

Care

The emperor tetra is one of the best tetras for a general community tank: lively, peaceful and handsome, with the males' trident-shaped tail and blue-green eye. Keep at least six, preferably ten or more. Males spar with each other in displays but rarely do any harm; a good group spreads this out. It is an active swimmer, so give it a tank with a base of at least 90 × 30 cm. It looks best in a planted tank with dim lighting or floating plants, a dark substrate and some driftwood. Aim for soft to medium water (about 1–12 dGH), pH roughly 5.0–7.5 and 23–27 °C. Virtually all emperor tetras in the trade are captive bred and are fairly unfussy about water chemistry and diet, so they are a good choice for beginners. Keep the water clean with regular partial changes. A darker 'black emperor' form is also sold. FishBase lists the wild species as Data Deficient on the IUCN Red List. Males can be told apart by their metallic blue eyes, while females have metallic green eyes; the IUCN lists the species as Data Deficient. Sources: Seriously Fish (seriouslyfish.com/species/nematobrycon-palmeri/); FishBase (fishbase.se/summary/Nematobrycon-palmeri.html); Wikipedia (en.wikipedia.org/wiki/Nematobryconpalmeri). Checked October 2026.

Diet

A micropredator of small insects and crustaceans in the wild. It accepts dried foods of a suitable size, but should not be fed on these alone – give small live and frozen foods such as daphnia, brine shrimp and bloodworm regularly for good colour and condition.

Breeding

Not difficult to breed. Males are larger and more colourful, with extended fins and a blue iris; females have a green iris. Spawn a well-conditioned pair or group in a separate, dimly lit tank with soft acidic water and fine-leaved plants or spawning mops. Remove the adults (or the eggs) as they eat eggs. Eggs hatch in 24–36 hours and the fry are free-swimming in 4–5 days; start them on infusoria-type foods, then brine shrimp nauplii.

Compatibility and tank mates

Mixes well with livebearers, danios, rasboras, other tetras, Corydoras and other peaceful bottom dwellers. It is generally safe with most gouramis and dwarf cichlids, but keep it away from larger, predatory fish.

Last updated 4 October 2026. Community-edited care guide on Aquatic-Auctions.

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