Black tetra fish: Characteristics, reproduction, care and more…

One of the most popular fish in aquariums is the Black tetra  fish (Gymnocorymbus Ternetzi) which is highly recommended for beginners since it’s a very resistant fish, has no great demands and is easy to breed.

Moreover, it worth mentioning that the black tetra looks just stunning in community aquariums. Today we will know them better.


Animalia Kingdom Phylum: Chordata Class: Actinopterygii  Subclass: Neopterygii  Order: Characiforms  Family: Characid  Genus: Gymnocorymbus  Species: G. ternetzi

Black Tetra:Description

The black tetra is a species of rounded and compressed body on its sides that has a length of 7.5 cm in total diameter.

However, it seldom  exceeds five centimeters in diameter.

The body  is black or grayish and they have two vertical black stripes.

Their dorsal and anal fins are highly developed and are similar to a skirt with most of its mass in the lower half of the body. The black color they show in their youth phase fades to gray as they mature.

Black tetra is a freshwater fish belonging to the Characidae family and it’s worth noting that there is another fish named with the same name, but it’s important not to confuse them since they aren’t the same species.

The other one is the false Black tetra Fish (Gymnocorymbus thayeri.)

It’s possible that some species are leucistic and / or albino, as some people usually give them color injections to make them more attractive.

This is a somewhat cruel practice that is also applied with molly fish. Hearts faces and others are usually dyed in their bodies.

In their habitat Black tetra have a life expectancy of seven years, although in aquariums they usually only last three.

There are small differences between female and male black tetra, for example the male’s dorsal fin is narrower and pointed than that of females.

In addition, the male front part of the skirt or anal fin is remarkably wide while the skirt of the female tends to run parallel to the stomach line.

Moreover mature females are usually stronger than males.

There are white, pink and blue varieties. As indicated above some of these specimens are painted artificially causing great pain to the black tetras.

These are sold as natural fish but that is nothing more than a hoax, the species that are painted are known as Blueberry Tetra, Strawberry Tetra or Rainbow Tetra. We invite you to read our article the anatomy of fish to learn about this interesting topic

 let’s meet them

Where do Black Tetras Inhabit?

The Mamoré river, in the Amazon basin itself, runs mainly through Bolivia, also passing through Brazil. One of its tributaries has an important route of 1530 km, of which 970 delimit the border between two countries: in Bolivia they call it the Iténez river, and in Brazil it is known as the Guaporé river.

The Paraguay River is one of the most important in South America, covering 4 countries: Brazil, Bolivia, Argentina and Paraguay.

The monjitas (as they are known in Spanish) or black tetras are distributed in the basins of the Itenez / Guaporé and Paraguay rivers.

Their favorite habitat are small streams, tributaries and currents with very slow water movements, marked mainly by the presence of a very dense vegetation.

In the aquarium they have a great capacity to adapt to different environments, but the ideal conditions will be to provide an aquarium of a minimum of 60 cm long for a small group of 6 – 8 specimens.

With little water flow, and a decoration to base of logs, roots and density of plants, among which we have floating plants that allow to attenuate the light.

Let’s learn a little bit about their habitat

What Does the Black Tetra Feed On?

The Black tetra is omnivorous and in nature its diet consists of worms, insects and invertebrates and occasionally small amounts of algae and plant matter. This diet should be reproduced as closely as possible in home a aquarium which is relatively easy since they are enthusiastic eaters.

It’s highly recommended to use high quality flake food and should be fed daily, with occasional administration of live or frozen foods and vegetables.

Flake foods should be provided once a day and only the amount they can eat.

The easiest live foods to provide are mosquito larvae daphnia, black worms and brine shrimp.

Live food is better but frozen foods are still a good option and are much easier to find during the winter months, among their favorite frozen foods we can mention.

    • Blood worms.
    • Black worms.
    • Daphnia
    • Brine shrimp.

Let’s learn about brine shrimp

How Do Black Tetra Fish Reproduce?

The Black tetra is oviparous. It’s a very prolific species and relatively easy to reproduce. It’s best to use a breeding aquarium of about 50 liters (the stalls are usually numerous) with abundant vegetation, preferably with a thin leaf, and softer water, a somewhat higher temperature than the main aquarium and in low light. 

The bottom may be covered by a mesh or marbles.

During the courtship the male swims with the fins deployed in a circle or zigzag around the female until he lays between 300 and 400 eggs.

The larvae hatch after 18-26 hours and once they have consumed the yolk sac they should be fed first with infusoria and later with artemia nauplii.

After the laying it’s advisable to remove the parents since the chances of eating eggs or fry are very high.

For the best success of the project, female and male should be c

Onditioned separately for 7 to 10 days before spawning, feeding them with a lot of small, live foods, also frozen foods.

For the reproduction of  black  tetras the breeding tank must have a temperature higher than the main tank approximately 27.8 at 30 ° C, with a neutral PH, and a water hardness below 15 Dgh.

Moreover, it’s necessary to maintain a dimly lit.  It’s also important to have a group of spawning mops or java moss, which will also give the female a place to deposit the adhesive eggs.

A mesh layer also works if it’s wide enough for the eggs to pass through it, but small enough to keep the parents out. Black tetras usually eat their eggs like other fish, for example zebrafish.

Black Tetras in Aquariums

This species is easy to care and is considered ideal for beginners. Simply provide quality water and keep it clean.

Keep in mind that aquariums are closed systems and regardless of size, they all need some maintenance.

Over time, the decomposition of organic matter, nitrates and phosphates accumulate and the hardness of the water increases due to evaporation.

To combat these ever changing conditions, water must be replaced regularly, (at least 25 to 50% every two weeks), especially if the tank is densely supplied.

Tetra Fish can be housed in aquariums as small as 10 gallons of water, but any committed aquarist must consider at least 29 gallons, since larger tanks provide not only more space to move comfortably.

Moreover, they also allow parameters to be much more stable in the water so the fish will be healthier in the long term.

black tetra fish : java mossOne of the reasons why black tetra fish require a relatively large aquarium is that they must be kept in groups of at least five individuals, since they are fish that socialize in shoals in their natural habitat.

If they are kept in smaller groups than this, they will be always stressed and won’t be friendly to other fish and a fish that has a life in this way will be more susceptible to disease, which can lead to a short life expectancy.

Any tank containing  black tetra fish must be heavily planted, and some of the easiest plants to add are swords from Amazon, Java Moss, Java Ferns, Hygrophila Polysperma and Water Wisteria, the addition of floating plants will also be appreciated, and these help to Cover up the light in the tank.

The duckweed and the frogbit of the Amazon are generally the easiest floating plants for their implementation, but if you wish you can also enter some more difficult floating plants such as lettuce or water hyacinth which is only possible if you have an open aquarium .

We invite you to read our article fish for fish tanks to learn more about aquarium settings

let’s learn about java moss in aquariums

Do you require any Special Filters?

When it comes to choosing a filter for the aquarium with black tetra fish, there is no special requirement in this regard; a HOB filter would be very suitable. This also depends on the size of the aquarium, a bottle filter could be a good option, but it’s generally excessive for a fish like this.

Setting the aquarium

Since they are very active swimmers, black tetra fish should be kept in a tank at least 20 inches long and ideally 15 or more gallons of water.

They thrive in soft and filtered water, and usually prefer plant cover and a darker gravel substrate.

It should be noted that they also need open areas to swim freely; in addition, the tank must be covered safely, since these fish are expert jumpers and will probably jump if they have the opportunity.

To get the best from black tetra fish, it’s suggested to mount a biotype tank. For the substrate, it’s suggested that river sand with some wood particles and twisted roots be used.

Moreover, some dry leaves can be added to the sand, which stains the water of a light brown color.

It’s necessary to replace the leaves several times a month and take into account that a weak lighting will make the color of the black tetra fish more vibrant.



The minimum size of the tank must be 57 liters, the need for lighting is moderate to normal. In terms of  water temperature, it must be between 21.1 ° to 26.1 ° C to raise fish it’s necessary that the temperature is higher; the ideal would be from 27.8 to 30 ° C. The Ph should be between 5.8 to 8.5, water hardness must be between 3 to 30 dGH.

let’s learn about biotype aquriums

Behavior and Compatibility

Black tetras are considered affable and beautiful since they are really fast and lively.

However, it’s necessary to create an environment where they don’t feel threatened since otherwise black tetras may behave nervously. The latter is achieved with a level of dim darkness and an aquarium filter that can create currents.

When a black tetra does not feel well in an aquarium, he shows it by standing still, mixing with the environment and hiding in the vegetation.

If you want to give him company, you can also do it by creating a school of between 8 or 10 specimens of his class.

They like to be in a group, they play chasing each other and they don’t hurt themselves, so you won’t have to worry about anything.

With age they tend to be calmer and less active than in their more youthful stage.

They aren’t  usually aggressive, except with long-finned fish … which are usually chased by the aquarium. It’s not convenient to mix with Guppys or Scalars, it’s best to mix them with other Tetra fis

Other Species

Let’s meet other species witin the family

Gold black Skirt Tetra (Socolof’s Tetra)

This tetra reaches a maximum length of about 5.5 cm and is, like its famous relative, a pretty and undemanding fish.

When they reach around 2 cm Goldback Skirt tetras exhibit their prettiest color.

However, even fully grown fish look very nice because of their unusual body shape and the golden back.

Black false tetra(Gymnocorymbus thayeri)

Gymnocorymbus thayeri is a species of fish of the family Characidae in the order of the Characiformes. Males can reach 5 cm in total length.

Black false tetras  live in tropical climate zones between 23 ° C – 27 ° C temperature in South America: Amazon River basin in Bolivia and Colombia, Orinoco River, Guyana and Trinidad and Tobago.

They are found in shallow to mid-level freshwater rivers and river basins. They feed on small crustaceans, insects, worms.

let’s enyoy them

Compatible Species with  Black tetras

Silver Fish

Also known by its scientific name Metynnis argenteus, this is a species of Serrasalminae endemic to the Tapajós river basin in Brazil..

Round-bodied and laterally compressed, in normal conditions Metynnis argenteus is of a uniform silver color, which sometimes shows a vague red coloration in the fins and around the throat. Commonly seen for sale as juveniles about two inches long, silver fish are peaceful fish.

Females bred in captivity can reach a length of between five and six inches while males tend to be much smaller.

In good condition, females tend to be fuller in the womb than males, while males develop slightly longer fins as they grow.

During courtship and rearing, males develop two large, very prominent black spots. One on top of the other, just behind the base of the pectoral fins, the red coloration of the fins deepens and black borders contrast.

Some male specimens may also show other large dark spots on the flanks, females show little or no color variation during courtship and breeding. We invite you to read our article silver fish to learn about this species.

Platy fish

Also known as southern platy, common platy or moonfish, its scientific name is Xiphophorus maculatus. The play is a species of freshwater fish of the family Poecilidae.

This species is closely related to the green sword and can be crossed with it. It’s native to an area of ​​North and Central America that extends from Veracruz, Mexico, north of Belize.

The platy grows to a maximum total length of 6.0 centimeters. The sexual dimorphism is mild, being the male’s caudal fin more pointed. Moreover the male’s anal fin has evolved into a gonopodium, a stick-shaped organ used for reproduction. The female anal fin is fan-shaped.

The wild varieties are monotonous in color, lacking the dark lateral line distinctly common to many species of Xiphophorus.

This fish prefers the slow waters of the canals, ditches and hot springs. The platy fish is omnivorous and therefore its diet includes both plants and small crustaceans, insects and annelid worms.

Other interesting facts about Platy fish

Breeders have developed a multitude of color varieties, for example: orange, red, yellow, red and black or black and white, which are common for fans of goldfish for aquariums of small species.

We invite you to read our article platy fish to learn about these striking fish

Neon fish

One of the best combinations to include in the aquarium along with the black tetra fish is undoubtedly the neon tetra fish, whose scientific name is Paracheirodon innesi. This is a freshwater fish of the Characidae family of the order Characiformes.

This species is native to dark waters and also inhabits clear waters in southeastern Colombia, eastern Peru and western Brazil,

There are also specimens in the tributaries of the Solimões, where the water is between 20 and 26 ° C, but it’s not found in the white-water rivers of Andean origin.

Its bright coloration makes the fish more visible than other species that inhabit the currents of dark waters, and is also the main reason for its popularity among tropical fish fans.

The tetra neon has a light blue back over a silvery white abdomen and is characterized by an iridescent blue horizontal stripe along each side of the fish, from its nose to the base of the fat fin and an iridescent red stripe that begins in the center of the body and subsequently extends to the base of the caudal fin.

Rarely, these fish develop a dark olive green lining on their backs.

The fish is partially transparent including the fins except for its marks, during the night, blue and red turn gray or black when the fish rests and reactivates once in the morning, it grows to approximately 3 cm in total length.

Sexual dimorphism is mild, with the female with a slightly larger belly, and a bent iridescent stripe instead of the male’s straight stripe, they have recently appeared in a variety of long fin

While commercially produced neon tetras have adapted well to a wide range of water conditions, very soft and acidic waters inhabit the wild that are generally colder than the 25 ° C where most of the water is maintained. Tropical aquariums can have a lifespan of up to ten years, usually around five in an aquarium.

Let’s enjoy them one more time…



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