Black Skirt Tetra

Gymnocorymbus ternetzi

Characins

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.

At a Glance

Adult Size7 cm
Body ShapeCompressed
Growth RateModerate
TemperamentMostly Peaceful
Water TypeFreshwater Only
Flow PreferenceModerate
Waste OutputLow
StockingSchool of 6+

Tank Requirements

Minimum Volume55 L
Minimum Length60 cm
FlowModerate
Water TypeFreshwater Only
Must-Haves in the Tank
Plants - Densely covered

Water Parameters

Temperature2026°C
pH68
Hardness315 dGH

Temperament & Compatibility

Aggression LevelMostly Peaceful
4/10
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 SwimmerFin Nipper

Available Varieties

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

Standard (Black Skirt)

The natural dark coloration. They feature distinct black vertical bands and a dark, flowing anal fin (the 'skirt'). The dark colors often fade to silvery-grey as the fish ages.

Same care requirements as the base species

Also known as: Black Widow, Wild Type, Standard

White Skirt Tetra

A naturally occurring, selectively bred leucistic (light-colored) morph of the Black Skirt Tetra. Care and behavior are identical to the standard form.

Same care requirements as the base species

Also known as: Gold Skirt, Albino, Leucistic

Long Finned Morph

Selectively bred for elongated, flowing fins. They require lower water flow to prevent exhaustion and are more vulnerable to being nipped by other fish.

Differs in 2 traits from base species

Also known as: Longfin Black Skirt, Hi-fin, Long Finned White Skirt

FlowLow
Behavior Traits
Hyperactive / Fast SwimmerFin NipperLong Finned (Nipper Target)

GloFish Tetra

Genetically modified White Skirt Tetras that fluoresce bright neon colors under blue/UV lighting. Their husbandry, temperament, and size are entirely identical to standard Skirt Tetras.

Same care requirements as the base species

Also known as: Glo Tetra, Cosmic Blue, Electric Green, Galactic Purple, Sunburst Orange, Moonrise Pink, Starfire Red

Black Skirt Tetra Care Guide Summary

The Black Skirt Tetra, scientifically known as Gymnocorymbus ternetzi, belongs to the Characins family group. Adults reach a maximum size of approximately 7 cm and have a compressed body shape with a moderate growth rate. Classified as mostly peaceful, this species primarily occupies the mid-level zone of the aquarium and produces a low level of biological waste.

To thrive, the Black Skirt Tetra requires a freshwater only aquarium with a minimum volume of 55 litres and a tank length of at least 60 cm. Water temperature should be maintained between 20°C and 26°C, with a pH range of 68 and a general hardness of 315 dGH. A moderate water flow is preferred.

The Black Skirt Tetra is a rewarding species to keep, provided its core environmental needs are met. This species is available in 4 varieties: Standard (Black Skirt), White Skirt Tetra, Long Finned Morph, and GloFish Tetra. 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.

Black Skirt Tetra Habitat Setup

When setting up an aquarium for the Black Skirt 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 dense planting to provide cover, break sightlines, and reduce stress.

Black Skirt Tetra Compatibility Notes

Classified as mostly peaceful, the Black Skirt 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, avoid housing with slow-moving or long-finned species that may become targets for fin nipping and 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.

Frequently Asked Questions About Black Skirt Tetra

How big does Black Skirt Tetra get?+
Black Skirt Tetra (Gymnocorymbus ternetzi) typically reaches a maximum adult size of approximately 7 cm. They have a compressed body shape and a moderate growth rate.
What tank size does Black Skirt Tetra need?+
A minimum aquarium volume of 55 litres and a tank length of at least 60 cm are recommended for Black Skirt Tetra. This ensures enough swimming space and helps maintain stable water conditions.
What water parameters does Black Skirt Tetra need?+
Black Skirt Tetra thrives in freshwater only conditions with a temperature range of 20–26°C, a pH between 6 and 8, and a general hardness of 3–15 dGH. A moderate water flow is preferred.
Is Black Skirt Tetra peaceful or aggressive?+
Black Skirt Tetra is classified as mostly peaceful with an aggression score of 4 out of 10. They are generally well-suited to peaceful community tanks.
How many Black Skirt Tetra should be kept together?+
Black Skirt 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 Black Skirt Tetra have any special tank requirements?+
Yes. Black Skirt Tetra benefits from plants - densely covered in the aquarium. These features help replicate their natural habitat and promote overall health and well-being.

Similar Species

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Characins
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Neon Tetra

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Pictus Catfish

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Catfish
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An extremely active, striking silver catfish with black spots and incredibly long barbels, native to South America. While peaceful toward similarly sized tank mates, they are highly effective nocturnal predators that will easily swallow small fish (like Neon Tetras) whole. They are scaleless and possess sharp pectoral spines that can easily become entangled in aquarium nets.