Black skirt tetra
The black skirt or black widow tetra, Gymnocorymbus ternetzi, comes from the Paraguay and Guaporé river basins in South America.
It is a deep-bodied silver fish with two vertical black bars and a broad dark anal fin that gives it the skirted outline.
It reaches five or six centimetres and lives around five years. It is hardy, cheap and widely sold as a beginner fish, all of which is fair. The part usually left out is that it nips fins — a small group in a tank with a betta, an angelfish or a guppy will pester them constantly — and that the black fades to grey as the fish ages, which is normal rather than a sign of illness.
- Origin
- Paraguay and Guaporé basins, South America
- Adult size
- 5–6 cm
- Lifespan
- About 5 years
- Minimum tank
- 75 litres for a group of six or more
- Temperature
- 20–26°C
- Temperament
- Peaceful in a group, but a persistent fin-nipper
Related: Angelfish · Betta · Goldfish · Black moor
2 black skirt tetra photos, newest first
Living with a black skirt tetra
Keep at least six, and preferably more. A small group nips; a large group directs that behaviour at each other and largely leaves tankmates alone. This is the single most effective fix for the species' reputation.
Do not house them with long-finned fish. Bettas, guppies, angelfish and fancy goldfish all end up with shredded fins.
They are undemanding about water and tolerate a wide temperature range, which is what makes them genuinely good beginner fish.
Give them open swimming space with planting around the edges.
Dyed and artificially coloured varieties are widely sold. The colour is injected or the fish is dipped, it fades within months, and the process kills a large proportion of the fish it is done to.
General guidance, not veterinary advice. Individual fishs vary, and anything about a specific animal is a question for a vet who has seen it.
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