All fish / Characidae

Black Widow Tetra

Gymnocorymbus ternetzi

Also known as black tetra, black skirt tetra, blackskirt tetra, black widow, petticoat tetra, long fin black tetra, white skirt tetra, glofish tetra, black tetra longfin, skirt tetra, ปลาเททร้าดำ, ปลากระโปรงดำ

This is a deep-bodied silver tetra with two dark vertical bars at the front and a large black anal fin shaped like a skirt. The black colour fades to grey as the fish gets older. It is hardy and cheap, and comes in long-finned, white and dyed or GloFish forms, so it is a common pick for a first community tank.

Care at a glance

Care level

Easy

Temperament

Semi

Adult size

5 cm

Temperature

20 to 26 °C

pH

6 to 7.5

Smallest tank

80 litres

Keep as

Shoal of 6 or more

Diet

Omnivore: flakes, small pellets, frozen bloodworm, brine shrimp and daphnia

Swims

Middle of the tank

Lifespan

3 to 5 years

Water

Freshwater

Wild range

South America: Paraguay and Guaporé river basins in Brazil, Bolivia, Paraguay and Argentina

Breeding

It scatters its eggs among fine-leaved plants and the parents will eat them, so take the adults out once spawning is over. Breeding is easy in a separate tank with soft, slightly acidic water. The fry hatch in about a day and start on infusoria.

Good to know

It can nip fins, especially when kept in small groups, so do not house it with slow, long-finned fish such as bettas or angelfish. Some artificially coloured fish have been dyed or injected, and these are best avoided.