Black skirt tetra
Gymnocorymbus ternetzi
Deep body with dark vertical bars; long-finned companions are vulnerable. A social shoaling fish for a planted aquarium with open swimming space.
At a glance
- Scientific name
- Gymnocorymbus ternetzi
- Dutch name
- Zwarte tetra
- Water temperature
- 20–26 °C
- pH
- 6–7
- Adult length, up to approximately
- 6 cm SL
- Experience
- Basic knowledge
- General hardness (GH)
- 5–20 °dGH
- Starting footprint
- 75 × 30 cm
- Swimming or living zone
- Midwater
- Flow
- Moderate, with sheltered areas
This is a documented adult size, not a measured average. SL means body length excluding the tail fin. Sex, origin and cultivated form can affect size.
Care guidance; origin and captive breeding can change requirements. Some ranges are deliberately narrower than natural extremes in the source. Adjust water gradually and keep ammonia and nitrite at zero.
Tank sizes are editorial starting points for adults, not guarantees for a complete stocking plan. Group size, tank height, swimming length and territories may require a larger aquarium.
Origin
South America — Paraguay / Guaporé
Habitat & setup
Tropical rivers and tributary waters; provide cover and open swimming space.
Diet
Varied fine pellets or flakes, supplemented with suitable frozen or live food.
Behaviour & grouping
Group, preferably 8–10 or more.
Living with other animals
Choose alert species without long fins and keep a substantial group. Avoid bettas, long-finned guppies and other vulnerable fish.
Possible combinations to investigate further
- Bronze cory
21–26 °C · pH 6–7
Reproduction
Egg-laying; eggs and fry usually need separate rearing.
A suitable cover helps prevent escape and jumping. Protect intakes for small animals. Do not use copper-based fish medication with invertebrates.
Sources & image credits
Data compiled on: 2026-09-27. Species sources support identity and care; group sources give general starting points. Practical recommendations are an editorial synthesis.
Photo: Gymnocorymbus_ternetzi.JPG — emptyvi. CC BY-SA 3.0.