A striking, robust schooling fish from Colombia. Unlike many tetras, they do not swim in a tight shoal, preferring to loosely associate while males stake out small territories to display to females. They feature a bold black lateral line and iridescent purple/blue hues.
Emperor Tetra At a Glance
Emperor Tetra Tank Requirements
Will Emperor Tetra fit in your tank?
Care guides tell you what Emperor Tetra needs, the next question is whether your tank can safely provide it. Test Emperor Tetra against your tank size, maintenance needs, and the fish you already keep before you buy.
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Emperor Tetra Water Parameters
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Emperor Tetra Temperament & Compatibility
Emperor Tetra Varieties
Each variety inherits the species defaults above. Only differences are highlighted.
Male
Males are distinguished by brilliant metallic blue eyes, extended dorsal fins, and a unique trident-shaped tail caused by an elongated central ray. They establish small territories and routinely engage in harmless sparring displays.
Differs in 2 traits from base species
Also known as: Male Emperor, Standard
Female
Females have metallic green eyes, plumper bellies (especially when gravid), and shorter, standard fins lacking the extended central tail ray. They are completely peaceful and do not hold territories.
Differs in 2 traits from base species
Also known as: Female Emperor
Black Emperor (Morph)
A popular selectively bred melanistic color morph where the black lateral stripe bleeds to cover most of the lower body. Care and sexual dimorphism are identical to the standard form.
Differs in 1 trait from base species
Also known as: Dark Emperor Tetra, Black Nematobrycon, Nematobrycon amphiloxus
Emperor Tetra Care Guide Summary
The Emperor Tetra, scientifically known as Nematobrycon palmeri, belongs to the Characins family group. Adults reach a maximum size of approximately 5 cm and have a fusiform body shape with a moderate growth rate. Classified as peaceful, this species primarily occupies the mid-level zone of the aquarium and produces a low level of biological waste.
To thrive, the Emperor Tetra requires a freshwater only aquarium with a minimum volume of 75 litres and a tank length of at least 60 cm. Water temperature should be maintained between 23°C and 27°C, with a pH range of 5–7.5 and a general hardness of 1–12 dGH. A moderate water flow is preferred.
Due to its specialist needs, the Emperor Tetra is best suited for fishkeepers who can provide a carefully planned setup. This species is available in 3 varieties: Male, Female, and Black Emperor (Morph). Each may differ slightly in size, temperament, or care needs, so it is worth checking the specific requirements of the variety you plan to keep.
Emperor Tetra Habitat Setup
When setting up an aquarium for the Emperor Tetra, a moderate water flow best suits their natural preferences. Because this species occupies the mid-level zone, the aquarium layout should prioritise open swimming space in the centre of the tank for free movement. Useful additions include leaf litter or blackwater tannins to replicate their natural soft-water habitat, dense planting to provide cover, break sightlines, and reduce stress, and floating plants to diffuse overhead light and create shaded areas. Keepers should note that a tight-fitting lid is essential, as this species is a known jumper.
Emperor Tetra Compatibility Notes
Classified as peaceful, the Emperor Tetra is a schooling species that feels most secure in a sizeable group, where natural shoaling behaviour reduces stress and brings out their best colours. When choosing tankmates, their energetic swimming style may stress more sedentary or timid species. Selecting tankmates that favour different water layers from the mid-level zone can help reduce competition and territorial overlap.
Emperor Tetra Recommended Tank Sizes
Standard aquarium sizes that meet the minimum volume and length requirements for Emperor Tetra.
20 Gallon High
20 Gallon Long
29 Gallon Standard
30 Gallon Breeder
36 Gallon Bowfront
40 Gallon Breeder
Show 17 more tank sizes
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Frequently Asked Questions About Emperor Tetra
How big does Emperor Tetra get?
Emperor Tetra (Nematobrycon palmeri) typically reaches a maximum adult size of approximately 5 cm. They have a fusiform body shape and a moderate growth rate.
What tank size does Emperor Tetra need?
A minimum aquarium volume of 75 litres and a tank length of at least 60 cm are recommended for Emperor Tetra. This ensures enough swimming space and helps maintain stable water conditions.
What water parameters does Emperor Tetra need?
Emperor Tetra thrives in freshwater only conditions with a temperature range of 23–27°C, a pH between 5 and 7.5, and a general hardness of 1–12 dGH. A moderate water flow is preferred.
Is Emperor Tetra peaceful or aggressive?
Emperor Tetra is classified as peaceful with an aggression score of 2 out of 10. They are generally well-suited to peaceful community tanks.
How many Emperor Tetra should be kept together?
Emperor Tetra is a schooling species and should be kept in groups of at least 6. Larger groups help distribute aggression and encourage natural schooling behaviour.
Does Emperor Tetra have any special tank requirements?
Yes. Emperor Tetra benefits from plants - densely covered, plants - floating, and leaf litter/blackwater in the aquarium. These features help replicate their natural habitat and promote overall health and well-being.
Does Emperor Tetra need a lid on the tank?
Yes. Emperor Tetra is a known jumper, and a tight-fitting lid or cover is essential to prevent escape. Even a small gap can be enough for a determined fish to leap out.
Top Tank Mates for Emperor Tetra
These fish are strong compatibility matches for Emperor Tetra based on water preferences, temperament, adult size, and tank behavior.
Bandit Cory
Corydoras metae
Ideal Tank MatesAsher Cory
Corydoras tukano
Ideal Tank MatesPanda Garra
Garra flavatra
Ideal Tank MatesJulii Corydoras (False Julii)
Corydoras trilineatus
Ideal Tank MatesWrestling Halfbeak
Dermogenys pusilla
Ideal Tank MatesMalaysian Trumpet Snail (MTS)
Melanoides tuberculata
Ideal Tank MatesPlants That Suit Emperor Tetra
These plants pair well with Emperor Tetra based on shared water preferences, layout fit, and how likely they are to hold up in the same aquarium.
Afzel's Anubias
Anubias afzelii
Amazon Sword
Echinodorus amazonicus
Anacharis
Egeria densa
Anubias Barteri
Anubias barteri
Baby Tears
Lindernia rotundifolia
Balansae
Cryptocoryne crispatula
Fish Similar to Emperor Tetra
Cardinal Tetra
Paracheirodon axelrodi
A stunning schooling fish native to the upper Orinoco and Rio Negro basins in South America. Famous for its brilliant iridescent blue line and a vivid red stripe that extends the full length of its body (distinguishing it from the Neon Tetra). They are strictly schooling fish that thrive in warm, acidic blackwater environments.
Serpae Tetra
Hyphessobrycon eques
A striking, deep-red schooling fish known for its highly active nature. While hardy and beautiful, Serpae Tetras are notorious fin-nippers. This behavior is usually localized within their own pecking order if kept in large enough schools (8+), but they should never be housed with slow-moving or long-finned tank mates like Bettas, Angelfish, or Gouramis.
Lemon Tetra
Hyphessobrycon pulchripinnis
A peaceful, deep-bodied schooling tetra known for its translucent yellow coloration and striking black and yellow fins. They are robust and active, making them an excellent choice for planted community aquariums. Their colors intensify significantly in a well-established tank with a dark substrate and proper schooling numbers.
Black Neon Tetra
Hyphessobrycon herbertaxelrodi
A peaceful, active schooling fish native to the Paraguay basin. Known for its striking contrast of a dark black lateral stripe underneath a glowing iridescent white/green-gold stripe. Excellent for community aquariums, particularly in planted setups or blackwater biotope tanks with subdued lighting.
Congo Tetra
Phenacogrammus interruptus
A stunning, large schooling fish native to the Congo River basin. Known for their iridescent rainbow colors and active swimming behavior. Despite their size, they are notoriously peaceful and can be skittish, requiring ample swimming space, dim lighting or floating plants, and peaceful tank mates. Avoid keeping with fin-nippers.
Black Skirt Tetra
Gymnocorymbus ternetzi
A very hardy, deep-bodied schooling tetra native to South America. They are incredibly popular for beginners but have a reputation as fin-nippers if kept in too small a group. A proper school disperses their internal bickering and largely prevents them from harassing other tank mates.