Congo Tetra

Phenacogrammus interruptus

Characins

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.

At a Glance

Adult Size8.5 cm
Body ShapeCompressed
Growth RateModerate
TemperamentPeaceful
Water TypeFreshwater Only
Flow PreferenceModerate
Waste OutputLow
StockingSchool of 6+

Tank Requirements

Minimum Volume110 L
Minimum Length90 cm
FlowModerate
Water TypeFreshwater Only
Must-Haves in the Tank
Plants - Densely coveredPlants - Floating

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Water Parameters

Temperature2328°C
pH67.5
Hardness318 dGH

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Temperament & Compatibility

Aggression LevelPeaceful
2/10
Where They Swim
Surface
Mid-level
Bottom
Stocking Guidelines
Keep at Least6 fish
Max per TankNo limit
Can Live Alone?No — needs a group
Behavior Traits
Hyperactive / Fast SwimmerShy / Slow Moving (Easily Stressed)Jumper (Lid Required)Fry Predator

Available Varieties

Each variety inherits the species defaults above. Only differences are highlighted.

Standard (Mixed School)

A standard mixed group of males and females. Congo Tetras are best kept in mixed-sex schools to encourage natural behavior and full male coloration.

Same care requirements as the base species

Also known as: Unsexed, Juvenile

Male

Males are larger, display highly vibrant iridescent colors (blue, red, gold), and develop long, feathery extensions on their dorsal and caudal fins.

Differs in 1 trait from base species

Also known as: Male Congo, Show Male

Behavior Traits
Hyperactive / Fast SwimmerShy / Slow Moving (Easily Stressed)Jumper (Lid Required)Fry PredatorLong Finned (Nipper Target)

Female

Females are significantly smaller, with a plumper belly, much shorter fins, and more subdued silvery-gold coloration compared to males.

Differs in 1 trait from base species

Also known as: Female Congo

Adult Size6 cm

Albino

A selectively bred albino/platinum morph lacking dark pigments. Males retain some iridescent colors and long finnage, but the body is primarily white/pink.

Differs in 1 trait from base species

Also known as: Albino Congo Tetra, Platinum

Behavior Traits
Hyperactive / Fast SwimmerShy / Slow Moving (Easily Stressed)Jumper (Lid Required)Fry Predator

Congo Tetra Care Guide Summary

The Congo Tetra, scientifically known as Phenacogrammus interruptus, belongs to the Characins family group. Adults reach a maximum size of approximately 8.5 cm and have a compressed body shape with a moderate growth rate. Classified as peaceful, this species primarily occupies the mid-level and surface zones of the aquarium and produces a low level of biological waste.

To thrive, the Congo Tetra requires a freshwater only aquarium with a minimum volume of 110 litres and a tank length of at least 90 cm. Water temperature should be maintained between 23°C and 28°C, with a pH range of 67.5 and a general hardness of 318 dGH. A moderate water flow is preferred. An aquarium test kit can help you monitor these values.

The Congo Tetra is a rewarding species to keep, provided its core environmental needs are met. This species is available in 4 varieties: Standard (Mixed School), Male, Female, and Albino. 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.

Congo Tetra Habitat Setup

When setting up an aquarium for the Congo Tetra, a moderate water flow best suits their natural preferences. Because this species occupies the mid-level and surface zones, the aquarium layout should prioritise adequate surface area with floating cover to make them feel secure near the waterline and open swimming space in the centre of the tank for free movement. Useful additions include 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.

Congo Tetra Compatibility Notes

Classified as peaceful, the Congo 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. Selecting tankmates that favour different water layers from the mid-level and surface zones can help reduce competition and territorial overlap.

Recommended Tank Sizes

Standard aquarium sizes that meet the minimum volume and length requirements for Congo Tetra.

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Frequently Asked Questions About Congo Tetra

How big does Congo Tetra get?

Congo Tetra (Phenacogrammus interruptus) typically reaches a maximum adult size of approximately 8.5 cm. They have a compressed body shape and a moderate growth rate.

What tank size does Congo Tetra need?

A minimum aquarium volume of 110 litres and a tank length of at least 90 cm are recommended for Congo Tetra. This ensures enough swimming space and helps maintain stable water conditions.

What water parameters does Congo Tetra need?

Congo Tetra thrives in freshwater only conditions with a temperature range of 23–28°C, a pH between 6 and 7.5, and a general hardness of 3–18 dGH. A moderate water flow is preferred.

Is Congo Tetra peaceful or aggressive?

Congo 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 Congo Tetra should be kept together?

Congo 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 Congo Tetra have any special tank requirements?

Yes. Congo Tetra benefits from plants - densely covered and plants - floating in the aquarium. These features help replicate their natural habitat and promote overall health and well-being.

Does Congo Tetra need a lid on the tank?

Yes. Congo 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.


Similar Species

Cardinal Tetra

Paracheirodon axelrodi

Characins
4 cm Peaceful

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.

Lemon Tetra

Hyphessobrycon pulchripinnis

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5 cm Peaceful

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.

Serpae Tetra

Hyphessobrycon eques

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4.5 cm Semi-Aggressive

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.

Emperor Tetra

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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.

Black Neon Tetra

Hyphessobrycon herbertaxelrodi

Characins
4 cm Peaceful

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.

Neon Tetra

Paracheirodon innesi

Characins
4 cm Peaceful

One of the most iconic freshwater fish in the hobby, famous for its striking iridescent blue and red stripes. Originally from the blackwater streams of the Amazon basin, they prefer slightly cooler water than many tropical fish and must be kept in schools to thrive, display natural behaviors, and feel secure.