Black Tetra (Gymnocorymbus ternetzi) Care Guide

Black Tetra (Gymnocorymbus ternetzi) Care Guide

The black tetra (Gymnocorymbus ternetzi) is a small fish that is native to tropical South America. 

This fish is popular in the aquarium hobby and can be found in many home tanks. 

In this care guide, we will discuss the proper tank parameters, diet, and care for black tetras. So, if you are interested in keeping these little beauties, keep reading!


Scientific Name
Gymnocorymbus ternetzi
Common NameBlack Widow Tetra, Petticoat Tetra, and Blackamoor. 
RioParaguay, Rio Guapore, Bolivia
Easy-going and peaceful
Minimum Tank Size
15 gallons
3 inches long at full maturity
Omnivore, eats most foods
Egg Layer
Ease of Care
6.0 to 7.5
70°F to 85°F 

Black Tetra Origins

The Black Widow Tetra is a small, brightly-colored fish from Brazil’s Guapore and Paraguay Rivers.

These fish thrive in heavily forested areas, which provide both shade and food for them.

They congregate near the water’s surface, eating insects, crustaceans, and small worms.

Black widow tetras were originally only available as wild-caught fish, but all specimens sold now are entirely captive-bred.

This has led to many new artificial variations of this popular fish.

Black Tetra Lifespan

The Black Skirt Tetra is a freshwater fish that can live for three to five years in the wild.

However, there have been cases where these fish have lived longer in captivity.

This species is sensitive to poor water quality and an uninteresting environment, so it’s critical to keep the tank clean and provide a calm home if you want your fish to live a long and healthy life.

What Are the Features of Black Tetra?


The black tetra is a small fish that typically grows to about three inches long.

It has a dark black body with a bright silver stripe running down its side.

These fish have a tetragonal form; they’re significantly bigger at the front of their bodies than at the rear.

The front of the fish decreases gradually towards the tail, where the fish’s anal and dorsal fins are positioned.


 Black Tetra is a popular aquarium fish known for its iridescent black coloration. 

The fins are generally dark gray or black, and the color of the fins is light Blackish silver. 

They also have two prominent, black, vertical bars that appear just posterior to the gills.

The Black Skirt Tetra’s most dominant feature is its Blackish silver tail. This tail fin is rounded and almost as long as the fish’s body. 


The black tetra grows to about 3 inches, making it one of the smaller tetras. 

Is Black Tetra Hardy?

Despite their small size, black tetras are a fairly hardy fish species that can adapt to various water conditions.

They are a popular choice for many aquarium enthusiasts due to their peaceful nature and striking appearance.

While they are not particularly difficult to care for, there are a few things to keep in mind to ensure your black tetras stay healthy and happy.

One of the most important things to remember when keeping black tetras is that they prefer to live in groups. 

In the wild, these fish are often found in schools of 20 or more individuals. While they can technically survive in smaller groups, they will be much happier and less stressed if they have plenty of friends to socialize with.

Black Tetra Availability

Black Skirt Tetras can be found at most of the Local Fish Shops throughout the year.

Despite their reputation as being difficult to breed, their availability in stores is not a problem that you will encounter frequently.

How to Care for Black Tetra?

The Black Skirt Tetra is one of our favorites among the various types of freshwater fish.

Not only do they have a unique appearance that sets them apart from other tank inhabitants, but they’re also really simple to keep.

This makes them a friendly choice for aquariums. Here are some tips to keep them healthy and happy.

Tank Size

Black Skirts enjoy swimming, so it is essential to provide plenty of room to ensure they don’t get cramped.

A minimum of 15 gallons is suggested; however, a 20-gallon tank is ideal for good measure.

Remember that larger tanks are always preferable if you intend to keep a large number of Black Skirt Tetras or establish a community tank with many species.

PH Level

When it comes to black tetras, it’s essential to maintain a pH level of 6.0-7.5. Anything outside of this range can be harmful to their health.

It’s also important to keep the water clean and free of pollutants. This will help ensure that your fish remain healthy and happy.


Black skirt tetras like dim illumination, so it’s recommended that you use a soft light when setting up their tank.

Too much light can cause stress, which is something you’ll want to avoid.

Also, use low-light plants and get an adjustable or multiple-mode lighting system.

This will allow you to create the ideal environment for your black tetras and keep them happy and healthy by adjusting the amount of light they receive.


The ideal temperature for these fish is around 70°F to 85°F, with the middle of this range being the ideal temperature.

Keeping the temperature in this range will help keep your black tetras happy and healthy.

To keep your water temperature stable, we recommend using an aquarium heater.

This will help ensure that your black tetras always have the ideal water temperature, no matter what the outside temperature is.


A good filter is essential for keeping your black tetras healthy.

While they don’t produce a lot of waste individually, a large school can quickly alter the water quality.

Your filter should keep ammonia and nitrate levels relatively low and get rid of all forms of waste.

In addition to a good filtration system, you’ll also need to keep an eye on the water quality in your tank.

Regular water changes are a must, and you should aim to do them at least once a week.

This will help keep ammonia and nitrate levels low and replenish any minerals that may be depleted over time.

Tank Decoration

One of the best things about keeping black tetras is how simple it is to care for them.

They’re not picky when it comes to tank decor, and they’ll do well in most setups. However, there are a few important points to bear in mind.

You don’t want any rough surfaces in your aquarium since they can be harmful to these active fish, and the best approach to accomplish this is to keep the plants out of the picture and around the tank’s perimeter.

This is a simple technique for providing enough open area for this species.

Black Tetra Diet

Black Skirt Tetras are omnivorous, so they aren’t picky when it comes to food.

In the wild, they will feed off plants and consume pretty much any insects they come across. This makes them an ideal addition to almost any tank, as they are tolerant of a wide variety of foods.

When kept in captivity, Black Skirt Tetras will readily eat flake food, Freeze-dried Bloodworms, and Brine Shrimp.

You can also feed them live or frozen insects such as Daphnia, Cyclops, and Artemia.

Black Tetra Compatibility

Black Tetras are one of the easier fish to care for and make great additions to any tank. They are very peaceful and will rarely exhibit signs of aggression.

The only thing you need to be wary about is their actions around long-finned fish.

We say this because this species is prone to nipping at flowy fins of betta fish or angelfish.

Other than that, Black Tetras can get along with other peaceful fish without any issues.

Black Tetra can be kept with the following fish:

  • Cardinal Tetra
  • Harlequin Rasbora
  • Dwarf Gourami
  • Neon Tetra
  • Celestial Pearl Danio
  • Honey Gourami
  • Chili Rasbora
  • Cory Catfish
  • Bolivian Rams


You should not mix a bigger fish with your black tetra because it would irritate it and perhaps devour it, and you should not put it with large-finned fish since they will nip their fins.

Is Black Tetra Reef Safe?

 Black Tetras are active swimmers and love to explore their surroundings, so it’s important to provide plenty of plants and hiding places in your tank.

They typically swim in the middle channel of the aquarium and like to nibble on plants, so be sure to include some hardy plants in your mix. 

They are also excellent fish for beginners and can be housed with various other freshwater fish.

Black Tetra Gender Difference

Female black tetras are generally larger than males and have a rounder physique.

The anal fin of the feminine runs parallel to the vertical black line on the stomach.

On the other hand, Males may have white spots on the caudal fin; they’re smaller, have a broader anal fin, and a narrower, more pointed dorsal fin, and the black line on their stomach is also steeper.

Black Tetra Breeding

Black Tetras are not challenging to keep in an aquarium, but they can be difficult to breed. 

They rarely breed in the aquarium and require completely different breeding set up to breed. 

The initiation of breeding begins when a male Black Skirt Tetra starts chasing a female restlessly, and when they pair up, the stomach size of the female will get bigger carrying eggs.

When the Black Tetra is ready to lay eggs, both parents will clean a smooth surface in the aquarium, usually a leaf of a plant. 

The female will then lay her eggs on this surface, and the male will follow behind and fertilize them. 

After the female lays the eggs, both parents will vigorously guard them until they hatch.

The eggs will hatch about three 18-30 hours and will begin to swim freely in a couple of days. 

Seven days after they are laid, the fry will be able to swim around on their own shortly after that. 

Some Possible Diseases and Prevention

Although the black tetra is a hardy fish, they still may suffer from diseases if not properly cared for. The most common diseases that affect black tetras include:


Hexamita is a parasitic infection that can cause a loss of appetite, weight loss, and even death in severe cases.

It can be acquired through contaminated foods or water. Thus, the most efficient method is to give medicated fish food, especially in the early stages of therapy.

But seriously affected fish may not be eating, in which case you need to add the medication to the water, typically at a dosage of 250 mg per 10 US gallons, once per day for at least three days.


Ich is unhealed scars on the face, resulting in a condition known as granuloma annulare. It’s a parasitic infection that comes on due to tension and creates visible white spots all over the body.

In most situations, water quality issues are the primary reason for stress-related Ich.

By performing routine water testing and making required adjustments, you can minimize the possibility of Ich difficulties.

Although it is not difficult to cure Ich, It is highly contagious.

So, infected fish must be isolated from the rest of your aquarium and treated with a copper-based medication.

Black Skirt Tetra FAQs

Are Black Skirt Tetras Schooling Fish?

Yes, They are schooling fish.

The Black Skirt Tetra prefers to live in groups of at least 8 fish, which helps reduce stress and fin nipping.

Can Black Skirt Tetras Live Alone?

Although they can be kept alone, it is not recommended as they love to shoal and be in a group.

Will Black Skirt Tetras Eat Neon Tetras?

Yes, Black Skirt Tetras may kill Neon Tetras.

However, if Black Skirt Tetras are maintained in a sufficient number (8+ minimal, 10+ optimum), have enough swimming area to decompress and hide, ample food to consume, and excellent water conditions, it is an improbable occurrence. 

Generally, Black Skirstetris is considered a peaceful fish.

Do I Need To Have a Separate Breeding Tank?

Yes, you will need to have a separate breeding tank for your black tetra fish.

They are susceptible to water quality and temperature changes, and their fry (baby fish) is extremely delicate.

A breeding tank should be at least 15 gallons in size, with a fine mesh net or screen on the top to keep the fry from escaping.

What Do Black Skirt Tetra Eggs Look Like?

Black tetra eggs are small and round, with a dark brown or black color.

They are often found in clusters on the bottom of streams or ponds.

Will Black Skirt Tetra Nip Fins?

Yes, black skirt tetras will nip fins.

They are schooling fish and like to be in groups, so they may nip at the other fish’s fins if you have other fish in the tank.

Is the Black Skirt Tetra Right For Your Aquarium?

The Black Skirt Tetra is a wonderful beginning freshwater fish.

They’re gorgeous and amusing, and it’s enjoyable to watch them swim in their school.

They’re also good community fish that can add color to your aquarium by adding a different hue.

They do, however, require an adequate number of schools (8+), space to swim and explore, and good water quality.

So, If you can give them the attention they require. They will add beauty and elegance to your neighborhood tank

Last Words

Black tetras are popular freshwater fish known for their sleek, black bodies and vibrant fins.

These beautiful fish are relatively easy to care for, making them good for beginner aquarists.

These peaceful fish can become great pets once you know how to care for them, so give them a try if you are interested!

We hope you enjoyed this article as much as we did.

If you have any questions, please share them with us in the comment section below.