Black Tetra 101: Care, Diet, Tank Size, Tank Mates & More

The Black Tetra (Gymnocorymbus ternetzi) is a very peaceful fish, ideal for community aquariums, both for its unique and vertically wide appearance and its size. They are found in South America, coming from the Guaporé and Paraguay river basins. They feature a silver base with black markings on the body and the tip of the fins.

Black Tetra
Black Tetra, Sven Kullander, CC BY-SA 4.0, via Wikimedia Commons

In this article, all issues involving this species and its maintenance in aquariums will be addressed and explained.

Species Summary

Distributed over a wide area of South America, comprising Argentina, Brazil, and Bolivia, Black Lemon is a species of tropical freshwater tetra belonging to the Characidae family. 

The species occurs in different slow-flowing streams and streams, usually with a predominance of vegetation on the surface. 

These tetras reach an ideal size for an aquarium, in addition to a contrast of unique colors, causing an incredible impact on the viewer, even when in small schools.

Overall, Black Tetra is a hardy and easily bred fish found in domestic aquariums worldwide, making it an ideal choice for beginning aquarists.

Care Guide

These fish are very adaptable and can live in community aquariums with other peaceful fish without any problems. Like other tetras, the Black Tetra must be kept in groups of at least six individuals of the species. In nature, they are found in large schools.

When taken care of, Black Tetra is a lovely fish, but they will show their best colors when given a balanced diet and in a suitable aquarium.

It is a resistant and easy-to-care fish, but that does not exclude knowing the species, its habits, and behaviors in depth. Like any other species, Black Tetra has its peculiarities, addressed and detailed in the following topics.

Tank Size

Black Tetras are very active fish and should be kept in schools, with ample free space for swimming. A 24″ x 15″ x 12″ or 18-gallon tank is a good size to start with a small school. But, like most shoal fish, the more space and the greater the number of individuals in the shoal, the better for the welfare of the fish.


As they are peaceful fish and coexist without problems with other animals, they can live with countless other species of fish in a community aquarium. Avoid aggressive species that could harm the Black Tetra or compete directly for food. 

This species may come to bite fish with very flashy and exuberant fins, such as Bettas and Guppies; in this case, pay extra attention to the aquarium.

Same Species Tanks

Black Tetras are often used as a single species in assemblages of Biotope-type aquariums, where the original location of the species is imitated.

It is a great species to be kept alone in a well-decorated aquarium. It is a large school species exhibiting many beautiful movements, with a beautiful black and white contrast that will grace any room.

Water Parameters

They are incredibly resistant fish that support a safe range of parameters.

This tetra can live with excellent quality in different parameters; the perfect temperature for its maintenance is 68 to 78 F. The ideal pH range is between 6.0 to 7.0 and hardness from 5 to 20°H.

This difference between hardness and pH is related to the particular region of origin and demonstrates the difference in parameters during the dry and rainy seasons.

What to Put in Their Tank

As for any other aquatic animal, an aquarium heater and a filtering system are essential to keep the tank with Black Tetra healthy. The filtration system should be well dimensioned. This species inhabits slow-flowing waters without creating a solid flow in the water.

The aquarium decor is not species critical. As it is a very active species, you should leave an open space for swimming along with calmer areas. 

They can inhabit either fine sand tanks with driftwood and a bed of dry leaves or densely planted aquariums; it will feel good in both environments, but they are more colorful when kept in a densely planted aquarium. Sandy, dark substrate will further enhance your colors. 

Although they prefer aquariums with low light, it adapts well to much lighter ones.

Common Diseases

Black Tetra are remarkably disease-resistant fish. Your fish should not present any problems when you make sure to keep the water quality and the tank in excellent condition and feed them good quality food. 

Like any other tetra, they may be prone to Neon Tetra Disease (NTD). Always quarantine new fish before placing them in the main aquarium.

Food and Diet

The Black Tetra, like other Tetras, is omnivorous. It feeds on small invertebrates, worms, crustaceans, insects, and mosquito larvae in their natural environment. It also feeds on plants.

This fish readily accepts commercial feeds in aquariums without problems, being great eaters. Dry, live, and fresh foods such as daphnia, brine shrimp, bloodworms, mosquito larvae, and others are highly beneficial to fish and should be fed regularly.

Providing a varied and balanced diet is essential for demonstrating its full potential. These fish are always hungry.


In an aquarium with all the correct parameters kept stable and with an ideal diet, this tetra can live for up to seven years, the most common being around four years.

In nature, these animals are prone to live less, as they are predisposed to diseases, attacks from other animals, and environmental causes.


Black Tetras have a body in a slightly tetragonal shape and predominantly silver, with a smooth gradient that progresses from a lighter color on the nose to a darker color, almost black, on the ventral fin, hence the name “Black Tetra.” 

Two vertical bars of black paint, one right after the gills, the other more in the center of the animal, are striking and distinctive features of this species.

There are some varieties such as the golden, albino (white with red eyes), and semi albino (white with black eyes) varieties and the veiled type that has long fins. There are colorful animals that are artificially dyed.


Black Tetra fish can quickly grow to almost 3 inches in length when well cared for and fed, but they more commonly grow to around 1.5 inches.

Behavior and Temperament

Black Tetra is a tropical fish species with peaceful behavior and can be kept in a community aquarium with fish of the same size. As it is a fish with sociable habits, it will be essential to keep a school of at least ten animals to show their natural behavior and more enhanced colors.

They are very active animals, occupying practically all strata of the tank; however, they prefer to feed on the surface.

Their behavior can slightly change if they feel uncomfortable, as they will be hidden amidst the vegetation. 

Although not necessarily aggressive with other fish species, the black tetras can show aggressive behavior among the members of the school, with the smaller and weaker fish subject to persecution and bites from the superior and dominant fish. 

They are peaceful with other fish species, occasionally nibbling slow or long fin fish.


Captive breeding is extremely simple and is carried out commercially and in domestic aquariums worldwide.

It is an oviparous species, where the female lays out sticky eggs. The male will lead the female to release the eggs, which he will then fertilize; most of the eggs will go to the bottom of the aquarium or will be in the middle of a clump of plants. Eggs hatch within three days, and larvae will be free-swimming within 48 hours. Parents do not exhibit any parental care.

Aquariums suitable for reproduction are usually used, with something in the background that prevents the parents from eating the eggs until they are removed to another location or spawning mops.

They are easily reproduced fish, where spontaneous reproduction can occur in any domestic aquarium, as long as it is well taken care of.

Gender Differences: Male vs. Female

There is apparent sexual dimorphism. Males are slightly smaller and have a more straight body, while females have a more rounder body. 

The dorsal and anal fins are more prominent in adult males. In females they are shorter and rounder.

Black Tetra Fun Facts

  • An ideal fish for any newbie to aquarium hobbyist and found in virtually any retail store around the planet.
  • This species is prevalent in aquariums and commercially reproduced in several countries, including the albino form.
  • To help trigger reproduction, add lots of vegetation, preferably thin-leaved plants, and use slightly softer water. Also, regarding the temperature, leave it a little higher than in the main aquarium and try to leave it with little light.
  • The male will swim in a circle or zigzag around the female until she lays between 300 and 400 eggs during mating.
  • Due to their color, they stand out much more if the substrate is dark and the aquarium is well planted.
  • It is known by many famous names, including ‘butterfly tetra,’ ‘black skirt tetra,’ and simply ‘black tetra.’


Britski, H.A., K.Z. de S> de Silimon and B.S. Lopes, 2007. Peixes do Pantanal: manual de identificaçäo, 2 ed. re. ampl. Brasília, DF: Embrapa Informaçäo Tecnológica, 227 p.

Lima, F.C.T., L.R. Malabarba, P.A. Buckup, J.F. Pezzi da Silva, R.P. Vari, A. Harold, R. Benine, O.T. Oyakawa, C.S. Pavanelli, N.A. Menezes, C.A.S. Lucena, M.C.S.L. Malabarba, Z.M.S. Lucena, R.E. Reis, F. Langeani, C. Moreira et al. …, 2003. Genera Incertae Sedis in Characidae. p. 106-168. In R.E. Reis, S.O. Kullander and C.J. Ferraris, Jr. (eds.) Checklist of the Freshwater Fishes of South and Central America. Porto Alegre: EDIPUCRS, Brasil.

Lopez, H.L., R.C. Menni and A.M. Miguelarena, 1987. Lista de los peces de agua dulce de la Argentina. Biologia Acuatica No. 12, 50 p. (Instituto de Limnologia “Dr. Raul A. Ringuelet”).

Robins, C.R., R.M. Bailey, C.E. Bond, J.R. Brooker, E.A. Lachner, R.N. Lea and W.B. Scott, 1991. World fishes important to North Americans. Exclusive of species from the continental waters of the United States and Canada. Am. Fish. Soc. Spec. Publ. (21):243 p.

Leave a Comment

Your email address will not be published.