Black widow tetra

Gymnocorymbus ternetzi

Also known as black skirt tetra

FreshwaterFish

Black widow tetra (Gymnocorymbus ternetzi) — emptyvi · CC BY-SA 3.0

Care at a glance

Temperature: 68–79°F; 20–26°C
pH: 6.0–7.5
Adult size: 2.4 in; 6 cm
Minimum tank: 15 gal; 55 L

Temperament: Mostly peaceful
Social behavior: Schooling
Swim level: Middle
Difficulty: Beginner
Breeding: Egg scatterer · Medium
Rarity: Common
Family: Characidae
Origin: Brazil, Bolivia, Argentina

Overview

The black widow tetra is a mostly peaceful schooler and a good first fish for a community tank.

Did you know

The dyed and long-finned versions of the black widow tetra sold in stores are the same species, just tank-altered. The injected colors fade over time, and the dyeing process is hard on the fish. The plain wild type is the better buy.

Caring for the black widow tetra

Keep black widow tetras in a group of six or more, in 15 gal (55 L) or larger. They do not need a strict biotope. A planted tank with some cover and a darker substrate suits them.

They handle a wide range, from 68 to 79°F (20 to 26°C) and a pH of 6.0 to 7.5. Feed flake, micro pellets and frozen bloodworms or daphnia.

They occupy the middle of the tank and are mostly peaceful, but they can nip fins. Skip slow, long-finned tank mates. They are egg scatterers with no parental care, and breeding them is of medium difficulty.

Good to know

The black widow tetra is a member of the family Characidae, with a tall, flattened body and dark vertical bars. The black tends to fade to gray as the fish age. Its conservation status is Least Concern.

In the wild

Black widow tetras come from slow rivers, streams and flooded forest in the Paraguay and Guaporé basins of South America. Those waters are soft, slightly acidic and shaded, and full of roots and leaf litter.

Varieties

The white skirt tetra is a leucistic form of this fish. Brightly colored skirt tetras are white skirts that have been dyed, a practice worth avoiding.

White skirt: leucistic white form
Longfin: flowing fins on black or white

Weekly picks

Tank mates

The black widow tetra is a mostly peaceful, schooling species that keeps to the middle. These picks share a community profile with it, are safe together in both directions, and overlap on water type, temperature and pH.

Check the full mix in the stocking calculator