Mourning Cloak Tetra

Tetras that only show black and gray on the body are rare. With their eye-catching coloration and high-contrast drawing, the black charcoal tetra stands out in every aquarium and has been one of the most popular aquarium fish for decades.


  • Name: Blackjack tetra, Gymnocorymbus ternetzi
  • System: Real tetras
  • Size: 4.5-5.5cm
  • Origin: southern Brazil to Argentina, basin of the Rio Guaporé and Rio Paraguay
  • Attitude: easy
  • Aquarium size: from 54 liters (60 cm)
  • pH value: 6-8
  • Water temperature: 22-26 ° C

Interesting Facts About the Mantle Tetra

Scientific name

Gymnocorymbus ternetzi.

Other names

Tetragonopterus ternetzi


  • Class: Actinopterygii (ray fins)
  • Order: Characiformes (tetras)
  • Family: Characidae (common tetras)
  • Genus: Gymnocorymbus
  • Species: Gymnocorymbus ternetzi (Mourning Mantle Tetra)


Black charcoal tetra can reach a length of a good 5 cm (females), while the males remain slightly smaller with a length of just under 5 cm.


The color of the body changes from a light gray on the head to a dark gray and almost black on the back of the body. There are two wide, black bands on the shoulder and just before the beginning of the dorsal fin. There are some shiny scales on the upper half of the body. Anal, dorsal and adipose fins are black-gray, the other fins are transparent. The colors fade a little with age. In the meantime, numerous cultivated forms are also on the market. The color form is known as “gold” is flesh-colored with a black pupil, while the “albino” variant is also flesh-colored, but with a red pupil. Long-finned fish are also known of all forms.


The black charcoal tetra has a fairly large distribution area and comes from the river systems of the Rio Guaporé and Rio Paraguay in southern Brazil and Argentina. There it occurs in various types of water, from slightly acidic to alkaline. That is why it is considered particularly adaptable.

Gender differences

The females are not only slightly larger than the males, but are also noticeably fuller and, due to the egg supply, also much higher back. Since the color is otherwise identical, the sexes are practically indistinguishable up to a size of just under 3 cm (reaching sexual maturity). Then the males also show a slightly more pointed dorsal fin.


Breeding is relatively easy. One to three pairs, the females with a clear spawning approach, are used in a small, somewhat darkened aquarium with a spawning grate or coarser gravel. A few clusters of finely feathered plants are added. The water shouldn’t be too hard with a pH below 7.5. Spawning takes place in the morning hours. The females can lay up to 500 eggs. The young hatch after just one day, but still feed on the yolk sac for 3-4 days and can then be reared with the finest live or dry food.

Life expectancy

Black charcoal tetra can live up to ten years, the age record is twelve years.

Interesting Facts


Black tetras are omnivores. They can also be fed exclusively with dry food, but live or frozen food is gladly accepted once or twice a week. If the fish are to be bred, conditioning with live or frozen food makes sense.

Group size

Even if the animals quarrel with each other, there is never any damage. So that they show their normal behavior and do not stand shyly in the plants, a group size of at least eight, better ten fish makes sense, whereby the gender composition is irrelevant.

Aquarium size

An aquarium of 54 L (60 cm edge length) is sufficient for a group of up to ten fish.

Pool equipment

The substrate should not be too dark so that the colors work better. Some plants should offer retreats. Wood and stones can complement the furnishings. It is important to have a free-swimming area that is not too small, in which the black charcoal tetra, which mainly inhabits the middle pelvic region, is mostly to be found.

Mourning cloak tetra socialize

All other peaceful, not too big fish can be socialized with the black charcoal tetras. Dwarf cichlids and armored catfish are particularly suitable for the floor area. If the aquarium is big enough, additional groups of tetras can be used.

Required water values

Black charcoal tetra is extremely adaptable and occurs naturally in areas with a wide variety of water conditions. That is why the hardness in the home aquarium is almost insignificant, the pH value can be between 6 and 8 and the temperature between 22 and 26 ° C, although short-term slight deviations up or down are well tolerated.

Mary Allen

Written by Mary Allen

Hello, I'm Mary! I've cared for many pet species including dogs, cats, guinea pigs, fish, and bearded dragons. I also have ten pets of my own currently. I've written many topics in this space including how-tos, informational articles, care guides, breed guides, and more.

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