Black Skirt Tetra (Gymnocorymbus ternetzi)

Common Name:

Black Skirt Tetra.

Scientific Name:

Gymnocorymbus ternetzi.

Other Names:

Black Widow Tetra, Black Tetra.

Family:

Tetragonopteridae (or the subfamily Tetragonopterinae within Characidae).

Distribution:

Rios Paraguay and Guapore in Bolivia and some of the southern rivers of Brazil.

Size:

Approx 2.5 inches or 7cm.

Diet:

Carnivorous, but most, since most available in the hobby are CBB, will take standard aquarium fare.

Water Temperature:

68-79 F (20-26 C).

Water Chemistry:

Since these are so common in the hobby, and they have been captive born and bred for generations, chemistry is not important.

pH:

6.0 to 8.0.

Life Span:

4-6 years on average, but they can live for much longer with proper care.

Description:

These fish have the flattened shape typical of the "larger" tetras. The standard "wild-type" morph has beautiful, understated finnage that is usually translucent, but may be tinged with a muted black. The body is a muted silvery-grey that is broken up by two to four thick black stripes. The ventral/caudal corner of the fish is often a faded black in colour.

The White Skirt has no black markings and a more translucent body, along with a muted pink stripe along the lateral line. This stripe ends in a pinkish-orange spot just above and behind the eye.

There are also grotesquely long-finned morphs of these fish.

Species Behaviour:

This is a peaceful shoaler that spends much of its time in the middle to upper strata of the tank.

Sexing:

Females are sometimes cited to be rounder and fuller than the males, which sometimes have white spots on the anal fin. The best way to tell is the width and orientation of the anal fin: the males have wider ones while the females' anal fins are almost parallel to their vertical stripes.

Breeding:

Slightly alkaline water that is very soft often leads to breeding. Some authors have suggested that separating a single pair from the larger shoal and placing them in a breeding tank will induce breeding. Others have removed multiple pairs at the same time. Most will suggest either the usage of a spawning mop or the removal of the parents soon after breeding. Be warned, though, that this is not an easy process, and that the parents will often upset the eggs within the tank as they are being removed. This is probably preferable to the egg-eating which may be the only other alternative.

White eggs may be nonfungused. As long as they aren't fuzzy, leave them alone, as they are likely to still be viable.

The fry are extremely small at their birth. They can be fed liquid egg layer fry foods until they are a week or two old.

Natural Conditions:

The Black Skirt Tetra spends its days in slow-moving creeks, many of which are almost choked with vegetation.

Minimum recommended tank size:

15 gallons is the absolute minimum for a small shoal.

Tank levels:

Top-Middle.

Feeding

In the wild, these eat insect larvae and crustaceans. They will, in a tank situation, take readily to commercially available flake and pellet foods, but appreciate a quantity of live foods within their diet.

Miscellaneous:

These were originally placed in Tetragonopterus, but they rarely are given that name in relevant aquarium literature. Amazingly, the Black Skirt is only found in aquarium literature as Gymnocorymbus ternetzi.

Albino Black Skirts are the fish most often sold as "Berry Tetras". These have been injected with dyes and are in no way, shape, or form colours that could be bred into G. ternetzi.

Photo Credit:

Photos 1-3 supplied courtesy and ^©Bee (blm672).
Photos 4-5 supplied courtesy and ^©Amy Janecek AKA Buddy.