Black Widow Tetra- Gymnocorymbus ternetzi

Origin Central South America
Maximum Size: 5cm
Care: Temp 24-28 deg (higher for breeding) any type of water without extremes.
Feeding: All food but preferably floating/surface insects.
Breeding: Black widow tetras will scatter their eggs on plants and after about two days the eggs will hatch, after another day the fry will be free swimming and can then be fed on liquifeed and infusoria.
Sexing: When mature the dark markings possessed by a young black widow tetra will lighten to a grayish shade. The females have a much narrower start (front) to their anal fin, in addition the females will be noticably deeper and wider in general due to the eggs inside them.
Comments: Black widows tetras are shoaling fish and should therfore, not be kept either singly or in pairs. This is predominantly a surface species requring other midwater and bottom feding in its tank to ensure that no bits of food are left uneaten.

The Black Tetra, Black Widow, or Blackskirt Tetra is very active and fast moving, but can tend towards fin nipping. Because of this they should not be kept with smaller fishes but do well in a community tank with larger fishes.

   These are schooling fish and like a well lighted tank with dense areas of bunched low vegetation. This leaves lots of open areas to swim in. They are hardy at 70° F to 90° F, but are prone to develop ick if kept in colder temperatures.

   The Black Tetra, Black Widow, or Blackskirt Tetra is distinguished by two vertical stripes and by what appears to be overly developed dorsal and anal fins making it appear as if though it has a "skirt", with most of its mass on the bottom half of the body. The fine black color changes to a gray in the adult and with age they become a more sedentary fish.

There is a long-finned variety first developed in Europe, the Long-fin Black Widow or Longfinned Black Tetra Gymnocorymbus ternetzi var., it is very popular and readily available. These fish are a bit more difficult to breed than the Black Tetra, Black Widow, or Blackskirt Tetra, probably because of their being highly inbred already.

   There are also natural white, pink and blue strains that have been developed. The White Tetra or Goldenskirt Tetra has become very common. It is sometimes artificially dyed in various pastels colors and sold as a Colored Tetra or Colored Skirt Tetra, or under various colored names such as the Blueberry Tetra, Strawberry Tetra, or Rainbow Tetra.

Black Widow tetra

Common name	Black Widow tetra
Scientific name	Gymnocorymbus ternetzi
Synonyms	Black tetra
Size	Around 2" (5cm) or slightly larger.
Origin	South America: Brazil and Paraguay
Tank setup	A planted tank, with open swimming space.
Compatibility	A peaceful community fish - long-finned varieties may fall victim to fin nippers.
Temperature	21-27oC (70-81oF)
Water chemistry	A wide range tolerated, but soft and slightly acidic (pH 6.0-7.0) prefered.
Feeding	Omnivorous: live, frozen and dry foods.
Sexing	Females are slightly larger with a rounder body. Males may show white spots on the tail fin.
Breeding	Eggs are scattered among fine-leaved plants and hatch in about a day. Being a typical egg scatterer, the parents will eat the eggs if given the opportunity.

A young Black Tetra. (JUN 98) Name: Gymnocorymbus ternetzi Size pH GH Temp Origin: Central America 7 cm 7.0 10 23oC The Black Tetra grows a little larger than most other tetra species, but they're just as peaceful and hardy as the others, being quite suitable for beginners. My 2 Black Tetras are about 4 cm, and exhibit the typical tetra behavior of picking on each other all the time, although it never seems to get serious. Their colors vary a lot according to health, mood and lighting levels, only occasionally reaching a really solid black tone. Most of the time their coloration is similar to the picture above. There is also an improved veiltail variety available in shops.

Name: Gymnocorymbus ternetzi		Size	pH	GH	Temp
Origin: South America		7 cm	7.0	10	25°C

The Black Tetra grows a little larger than most other tetra species, but they're just as peaceful and hardy as the others, being quite suitable for beginners. They exhibit the typical tetra behavior of picking on each other all the time, although it never seems to get serious. Their colors vary a lot according to health, mood and lighting levels, only occasionally reaching a really solid black tone. Most of the time their coloration is similar to the picture above. There is also an improved veiltail variety available in shops.

I have kept 4 of these fish in a 1 meter tank with 5 Giant Danios, 2 Zebra Danios, 2 Angels and a Pleco. They are very hardy. However, they are not friendly toward each other in the least! Their colors are much richer in subdued light.

This is one of the easiest tetras to spawn. They are egg scatterers so some kind of a grid on the bottom of the tank to protect the eggs is a good idea. Males are a little more colorful and fins a bit more exaggerated, but if you want a definitive way to sex them, run a wet finger across the anal fin of a netted fish. If it's a male, your finger will catch on tiny hooks on the fin that the male uses to keep the female nearer during spawning. They are not visible to the eye, but they can be felt by this method.

Black Tetras are also known as Black Skirt/Black Snail Tetras. They grow quite large and aren't friendly to each other, but are peaceful to any other fish. Sometimes if you have a larger one and a smaller one in the same tank the larger fish will pick on the other one. They are excellent beginner fish and live for a long time.

I've also got a pair of Black Tetras, and they change colour drastically under different levels of light. Turning on a lamp after a period of darkness usually sees them very black. With normal aquarium lights, they look like those in the picture. When I added white gravel to my fish tank, the strong reflection of the light on the gravel made the Tetras ghost white! Very nice! It's an interesting fish with exceptionally shiny scales.

My Tetras are relatively passive with one another, and I have found that if given enough room, they won't bother one another in the slightest. Their temper comes down to the water levels...I find that the harder the water, around 7.5 - 8.0 (yes 8.0!!!), these little guys tend to thrive, unbelievable but true.