Nematobrycon palmeri (Emperor Tetra)

05 July 2026

532

The Emperor Tetra (Nematobrycon palmeri) is a stunning, peaceful freshwater fish native to the Atrato and San Juan river basins in Colombia. Known for its regal purple and blue iridescence, striking black lateral stripe, and unique trident-shaped tail in males, it is a highly popular choice for planted community aquariums.

Overview

The Emperor Tetra is an elegant and robust tetra species that brings a touch of royalty to the freshwater aquarium. Unlike many other tetras, they do not need to be kept in massive schools to feel secure, though a small group is highly recommended. Their iridescent hues and the striking finnage of the males make them an eye-catching centerpiece for any planted setup.

Image of emperor tetra eu nz nematobrycon palmeri

Distribution and Habitat

Endemic to Colombia, the Emperor Tetra is predominantly found in the Atrato and San Juan river basins. They inhabit sluggish tributaries, small streams, and backwaters that are heavily shaded by dense rainforest canopies. The waters in their natural habitat are typically soft, slightly acidic, and rich in tannins from decaying leaf litter.

Description of Emperor Tetra

Body shape:

They possess an elongated and slightly deep body that is more robust than many typical slender tetras, giving them a substantial presence in the water.

Color:

Their coloration is spectacular, featuring a prominent, thick black lateral stripe running from the mouth to the tail. Above this stripe, the body reflects a stunning purplish-blue to silver iridescence.

Barbels:

They do not possess barbels.

Snout:

The snout is relatively short and pointed, equipped with a small, terminal mouth suited for picking small foods from the water column.

Eyes:

The eyes are large and striking, often featuring a metallic blue or green sheen on the upper part of the iris.

Fins:

The fins are generally a translucent yellow or greenish-yellow. In males, the dorsal fin is notably elongated and sickle-shaped.

The Tail:

The caudal fin is a defining feature, particularly in males, where the central black body stripe extends through the middle of the tail, creating a unique "trident" or three-pronged appearance.

Temper

The Emperor Tetra is generally a peaceful species, making it an excellent candidate for a community tank. Males will occasionally engage in mock battles to establish dominance and impress females, but these displays are harmless and rarely result in actual injury.

Sociality

While not as tightly schooling as some other tetras, they are a shoaling species and should be kept in groups of at least 5 to 6 individuals. A mixed-gender group allows for natural behaviors and vibrant coloration as males display to females.

Activity

They are active mid-to-top level swimmers. They spend much of their day exploring the tank, interacting with one another, and foraging for food among aquatic plants.

Keeping and Caring for Emperor Tetra

Tank size:

A minimum tank size of 20 gallons (approx. 75 liters) is recommended to provide ample swimming space and accommodate a proper shoal.

Water Parameters:

Temperature

Maintain the water temperature between 23-27°C (73-81°F).

pH

They thrive in slightly acidic to neutral water, with a pH range of 5.0 to 7.5.

Hardness

Soft to moderately hard water is ideal, ranging from 3 to 12 dGH.

Ammonia, Nitrite, Nitrate

Ammonia and Nitrite must be strictly maintained at 0 ppm. Nitrates should be kept below 20 ppm through regular water changes.

Lighting

Subdued to moderate lighting is preferred. Dimmer lighting not only mimics their shaded natural habitat but also brings out their best iridescent colors.

Water flow

A gentle to moderate water flow is best, simulating the sluggish streams they originate from.

Decorations and Plants

A heavily planted tank with dark substrate is ideal. Incorporate driftwood, floating plants to diffuse light, and dried leaf litter to provide tannins and natural hiding spots.

Diet

Emperor Tetras are omnivorous and not fussy eaters. In the aquarium, they will readily accept high-quality dry flakes and micro-pellets. To ensure optimal health and coloration, supplement their diet with live or frozen foods such as daphnia, bloodworms, and brine shrimp.

Some Feeding Tips

Feed them small amounts 1 to 2 times a day, offering only what they can consume within a couple of minutes to prevent water fouling.

Breeding

They are egg scatterers and relatively easy to breed. Set up a separate, dimly lit breeding tank with soft, acidic water and fine-leaved plants like Java Moss or spawning mops. Condition the pair with live foods. After spawning, the parents should be removed immediately as they will eat their own eggs. The fry typically hatch in 24-36 hours and become free-swimming a few days later, requiring infusoria or specialized fry food.

Conclusion

The Emperor Tetra is a magnificent and relatively hardy fish that rewards aquarists with dynamic behavior and breathtaking coloration. Whether you are a beginner or a seasoned hobbyist, a well-maintained planted tank featuring a shoal of these regal tetras is sure to be a captivating display.

Fish info

Care level: Easy - Moderate
Temperament: Peaceful
Adult size: 5 cm
Life expectancy: 4-6 years
Fish type: Tetra
Temperature : 23-27°C
pH: 5.0-7.5
Color Form: Black, Blue, Purple, Yellow

Related on Fishs

Leave your comments

Latest on Fishs

Dwarf Gourami Red (Trichogaster lalius)

Easy - Moderate

Asian labyrinth fish

The red dwarf gourami is a selectively bred color form of the dwarf gourami, a small labyrinth fish formerly widely known as Colisa lalia. It is suited to mature, planted community aquariums with gentle water movement and calm tank mates. Males can be territorial, especially when kept with females in confined conditions, so cover, visual barriers, and careful observation are important for a pair.
Cockatoo Cichlid Red (Apistogramma cacatuoides)

Moderate

South American dwarf cichlid

The Cockatoo Cichlid is a small South American dwarf cichlid valued for its personality, breeding behavior and colorful finnage. Apistogramma cacatuoides is generally adaptable when provided with clean, stable water, cover and a soft substrate. Males are larger and more vividly marked than females, while pairs become territorial around spawning sites. The supplied “red” designation most likely refers to a selectively bred color form; exact strain and sex confirmation cannot be established from the listing alone.
Discus (Symphysodon aequifasciatus) Care Guide

Difficult

South American freshwater cichlid

Symphysodon aequifasciatus is a large, laterally compressed cichlid from the Amazon Basin, valued for its calm behavior and striking disc-shaped body. It requires warm, clean, stable water and careful feeding, making it better suited to experienced aquarists. The supplied images show yellow, orange, red, white and dark color forms; cultivated strains can vary considerably, so exact variety identification from images alone is uncertain. Discus are social fish and generally thrive in groups rather than as isolated specimens.
Cape Lopez Killifish (Aphyosemion australe)

Moderate

West African non-annual killifish

The Cape Lopez killifish is a small, peaceful West African freshwater fish prized for its patterned body, flowing fins and manageable size. It inhabits slow-moving and temporary waters around coastal Gabon, including the Cape Lopez region. The supplied trade description identifies a pair as “Cape Lopez splendid carpets,” but this wording may describe a commercial strain rather than a formally recognized taxon. The image appears to show an orange form, so exact strain identification should be confirmed with the breeder or supplier.
Burton’s Mouthbrooder (Astatotilapia burtoni)

Moderate

East African haplochromine cichlid

Burton’s mouthbrooder, Astatotilapia burtoni, is a moderately aggressive East African haplochromine cichlid known for strong social hierarchies and maternal mouthbrooding. Males become more vividly patterned and defend territories, while females are generally less colorful and carry eggs and fry in the mouth. A pair requires a spacious, well-filtered aquarium with rocky cover, alkaline water and carefully selected tank mates. The supplied identification is consistent with Astatotilapia burtoni, although sex and locality form cannot be confirmed from the photographs alone.
Cyrtocara moorii (Blue Dolphin Cichlid) Care Guide

Moderate

Lake Malawi haplochromine cichlid

Cyrtocara moorii is a large, distinctive haplochromine cichlid from Lake Malawi, recognised for its blue adult coloration and rounded forehead, which becomes more pronounced with age. It is a maternal mouthbrooder and is generally less aggressive than many Malawi mbuna, but its size and territorial breeding behaviour require a spacious aquarium. The supplied images appear consistent with blue C. moorii, although photographs cannot confirm sex, locality, or whether the fish form a true bonded pair.
Blue Dwarf Gourami Pair (Trichogaster lalius)

Easy - Moderate

Peaceful labyrinth fish

The blue dwarf gourami is a selectively colored form of a small labyrinth fish native to the Indian subcontinent. It spends much of its time in the upper and middle aquarium, using its specialized labyrinth organ to breathe atmospheric air. Males can become territorial, especially when nesting, so a planted aquarium with calm tank mates, gentle flow, and surface cover is important. The supplied name uses Trichopodus lalius; Trichogaster lalius is the commonly used current combination.
Blue Acara (Aequidens pulcher)

Moderate

South American freshwater cichlid

The supplied label identifies these fish as Blue Acara, Aequidens pulcher, a South American freshwater cichlid often placed in the genus Andinoacara in current aquarium literature. The photograph is consistent with a blue acara, although a definitive identification cannot be confirmed from one image alone. This pair requires a spacious aquarium, stable water quality, hiding places and careful observation during breeding, when territorial behavior becomes stronger.
Julidochromis transcriptus: Black-and-White Slender Cichlid

Moderate

Lake Tanganyika rock-dwelling cichlid

Julidochromis transcriptus is a small rock-dwelling cichlid from Lake Tanganyika, recognized by its compact, elongated body and irregular black-and-white pattern. It is a territorial cave dweller that is best kept as an established pair in a carefully structured aquarium. The supplied fish are identified as a DNZ pair, although sex, collection locality, and precise geographic form cannot be verified from the supplied material alone.
Azur Cichlid (Sciaenochromis fryeri) Care Guide

Moderate

Lake Malawi haplochromine cichlid

The Azur cichlid is commonly sold as Sciaenochromis fryeri, a predatory haplochromine cichlid from Lake Malawi. Mature males develop vivid electric-blue coloration, while females and juveniles are generally less intensely colored. This fish is moderately aggressive and needs a spacious aquarium with rocky structure, alkaline, mineral-rich water, and carefully selected tank mates. The supplied source describes a DNZ pair, but sex and exact locality cannot be confirmed from the images alone. Identification confidence is therefore good but not absolute.
Marble Angelfish (Pterophyllum scalare)

Moderate

South American freshwater cichlid

The marble angelfish is a captive-bred color form of Pterophyllum scalare, a tall-bodied South American cichlid valued for its elegant fins and distinctive irregular black patterning. It needs a mature, spacious aquarium with excellent water quality, warm water and suitable tank mates. Although generally manageable, adults establish territories and may become assertive when pairing or spawning. The supplied source identifies two marble angelfish; exact lineage and strain details cannot be confirmed from the available information.
Gold Angelfish, Pterophyllum scalare

Moderate

Freshwater South American cichlid

The Gold Angelfish is an ornamental colour form of Pterophyllum scalare, a tall-bodied South American cichlid valued for its graceful movement and parental care. It needs a mature, spacious aquarium with substantial vertical clearance, stable warm water and carefully chosen tank mates. The supplied source identifies two fish as Gold Angelfish, although the accompanying images show several angelfish colour and fin forms, so the exact appearance of the supplied specimens cannot be confirmed from the images alone.
Zebra Angelfish (Pterophyllum scalare)

Moderate

South American freshwater cichlid

The Zebra Angelfish is a selectively bred form of Pterophyllum scalare, recognised by a silvery body with several dark vertical bars and the tall, laterally compressed shape typical of freshwater angelfish. The supplied images also show other angelfish colour forms, so the exact appearance of the listed pair cannot be confirmed from the image set alone. This South American cichlid is generally manageable for experienced community keepers, but its size, territorial breeding behaviour and need for a tall aquarium should be planned for carefully.
Black Angelfish (Pterophyllum scalare)

Moderate

South American freshwater cichlid

The supplied record identifies two black angelfish, most likely a domestic color form of Pterophyllum scalare. The photographs show several angelfish color patterns, so they should not be treated as proof that every pictured fish is black or that all belong to the same strain. Black angelfish retain the tall, laterally compressed body and extended fins typical of freshwater angelfish. They need a tall, mature aquarium, stable warm water, a varied diet, and carefully selected tank mates.
White Marble Angelfish (Pterophyllum scalare)

Moderate

Freshwater cichlid

The white marble angelfish is a selectively bred aquarium color form of Pterophyllum scalare, a tall-bodied South American cichlid valued for its elegant fins and distinctive irregular dark marbling. It is generally peaceful when young but can become territorial, especially when paired for spawning. Successful care depends on a tall aquarium, excellent water quality, suitable tank mates, and a varied carnivorous-omnivorous diet. The exact genetic strain shown cannot be confirmed from photographs alone.
Freshwater Angelfish Mix (Pterophyllum scalare)

Moderate

Freshwater cichlid

Freshwater angelfish are tall-bodied South American cichlids valued for their graceful movement and wide range of captive color forms. The supplied source identifies a mixed group as Pterophyllum scalare; the photographs show several forms, including striped, black, orange, white, silver and blue-toned fish. They are manageable for experienced beginners, but their adult height, territorial breeding behavior and tendency to eat small tank mates require thoughtful aquarium planning.