Black Skirt Tetra (Gymnocorymbus ternetzi) Care Sheet

One of the most common species you’re likely to come across–and maybe one of the reasons you may have gotten into the fishkeeping hobby in the first place–is the black skirt tetra. These fish have a beautiful and simple natural coloration but have also been bred to come in an assortment of colors and fin variations. Their easy care and schooling behavior make these fish a favorite for many!

Keep reading to find out everything you need to know about black skirt tetra care and keeping these fish in your own aquarium!


Gymnocorymbus ternetzi is commonly known as the black skirt tetra, black widow tetra, petticoat tetra, blackamoor, and the high-fin black skirt tetra.

These fish have become a very popular fish to selectively breed in the aquarium trade and this process has resulted in different variations, such as the white skirt tetra, long fin black skirt tetra, and colored skirt tetra.

G. ternetzi may also be confused with the black phantom tetra (Hyphessobrycon megalopterus) due to their similar appearances, but they are not even in the same genus!

Natural habitat

These tetras originate from the freshwater rivers of Brazil, Paraguay, and northeastern Argentina. In these regions, they are mostly concentrated in the Guapore and Paraguay River basins. It is believed that there is also a population in the Paraná and Paraíba do Sul Rivers, but this is likely the result of unnatural introduction.

These South American regions consist of small tributaries with slow-moving water and often have a lot of overhanging vegetation. Black skirt tetras can mostly be found near the surface of the water, feeding on insects, worms, and other food that falls over them.


These tetras are pretty easy to identify, even for a beginner. They have a deep silver body, marked by two vertical black stripes towards their head. Their dorsal and anal fins will also have black coloration, though some fish may have hardly any at all.

Since these fish are mostly exclusively bred within the aquarium trade, hobbyists and retailers have created a few different variations through careful breeding. At your local pet stores, you’re most likely to come across:

Long-finned skirt tetra. These fish have been selectively bred to express longer-than-usual ornate dorsal, anal, and caudal fins. These fish have similar patterns to regular Gymnocorymbus ternetzi, but may have more vibrant colors on their fins and may be a little larger overall.

White skirt tetra. These tetras do not exist naturally in the wild in this color variation. White skirt tetras are a type of selectively bred Gymnocorymbus ternetzi that has been made to express albinism. Some of these fish are artificially colored to create colored skirt tetras.

Colored skirt tetra. These artificially colored tetras come in a variety of pastel colors, from blues to reds to yellows. These fish are usually the product of white skirt tetras being injected with color dyes. This is a painful process and leads to a shortened lifespan of the fish. Though these fish appeal to the eye, the practice is unethical and often leads to an uncolored or dead fish in a couple of weeks.

Black Skirt Tetra

How big does a black skirt tetra get?

These tetras usually grow to around 2-3 inches (6-8 cm) but can vary depending on variety and quality of breeding. Also, expect your fish to live up to 2-3 years in a well-maintained aquarium!

How can you tell if a black skirt tetra is male or female?

Female black skirt tetras tend to be overall larger and plumper than males. Male fish will be slimmer and have a more pointed dorsal and anal fin than females.

Black skirt tetra tank requirements

Black skirt tetras don’t have many aquarium needs. As long as they are kept in a suitable aquarium size and water parameters are maintained, you will have no problem sustaining a school of these fish in your tank.

Black skirt tetras should be kept in groups of at least 6 and will need a minimum tank size of 20 gallons (75 L). They will need a stable water temperature between 72-82° F (22-27° C), with pH between 6.0-7.5, and KH between 4-8.

To help make your fish more at home in your aquarium, it is best to use a dark substrate and subdued lighting. Because these fish won’t venture down to the bottom of the aquarium often, substrate choice does not make too much of a difference; both sand and gravel will work fine! Low light-demanding plants and floating plants will also provide natural shelter and help dim lighting, but make sure to leave plenty of room for swimming.

To help darken the aquarium environment more, you can try adding Indian almond leaves; these leaves leak tannins, staining the water a light brown. These leaves have also been shown to help boost the overall health of the system and do not require any more maintenance. You can check out our full guide explaining when, why, and how to use Indian almond leaves here.

There shouldn’t be too much flow in the aquarium. While they are active swimmers and will move about in their school, they will not swim against the current like other species of fish.

Are black skirt tetras hardy?

Black skirt tetras are extremely hardy fish! They will forgive most water parameter issues and get along with other tank mates. The only thing you need to make sure is that water temperature remains stable.

These tetras will not do well in cooler temperatures, and can easily become sick if left exposed for too long. Keep your aquarium a nice tropical temperature and you should have no problems!

Always properly acclimate any new fish you receive before adding them to your tank. Quarantine in a separate tank for 2-4 weeks if possible.

Black skirt tetra tank mates

One of the great things about these fish is their ability to be housed with many other species. While these fish have sometimes been known to nips at longer fins, this can usually be fixed by keeping them in an appropriately-sized school. If you’re seeing your tetra nip at fins, try adding a couple more black skirts if your tank allows.

Besides other black skirt tetras, these peaceful fish can be kept with most tetra species, rasboras, danios, and docile bottom-feeders. Fish with long fins, like angelfish, should be avoided as tank mates.

How many black skirt tetras can you have in a school?

In the wild, these fish school in the hundreds and maybe even the thousands. Of course, in the aquarium, you are limited to how many you can have by bioload and behavior.

It is strongly recommended to keep at least 6 of these tetras together, with 8 being even more optimal for a smaller tank. Like other tetra species, black skirts will not do well alone and tend to stay hidden; they often get picked on by other fish which can quickly lead to disease and death.

A nice, healthy shoal will keep your fish active and in the front of your tank. For larger tanks, allow at least another 3 gallons (11.4 L) per additional fish.

Black skirt tetra behavior

Black skirts are active schoolers that like to stay in the middle and upper water columns. They can sometimes have the tendency to nip at longer fins. As long as they are kept in a larger tank and long-finned tank mates are avoided, this should not be too big of an issue.

Black skirt tetra diet

Black skirts are omnivorous fish and will readily eat a large variety of foods. For a healthy and colorful school, provide an assortment of flakes, live foods, and frozen foods. Live and frozen foods can consist of mosquito larvae, brine shrimp, bloodworms, and daphnia and will all be accepted by your fish.

Remember that these fish have tiny mouths so whatever food you feed should be easily bitten and swallowed!

Black Skirt Tetra

Breeding black skirt tetras

Black skirts are very easy to breed, though you will need a separate breeding tank as they scatter their eggs. This tank should be large enough to comfortably house a pair of tetras or a group; if wanting to try breeding as a group, try putting six females and six males together.

This breeding tank should be dimly lit and have fine-leaved plants, like Java moss, to catch the eggs; a spawning mop or mesh/crate can also be used as a substitute. It is especially important to keep the tank dim once the eggs are laid since both the eggs and fry are extremely sensitive to lighting.

This tank should be kept a little warmer, at a stable temperature between 82-86° F (27.8-30.0° C). Fish should be fed an assortment of frozen and live food, like brine shrimp and bloodworms.

Once your fish have spawned, remove them as soon as you have realized to prevent them from eating the eggs. These eggs will then hatch over the next couple of days and become free-swimming shortly after that. Feed the fry infusoria and then crushed foods once they start getting bigger. Wait until they have grown enough so that they can hold their own in your display tank or give them to another hobbyist!

It is possible to spawn in your main display, but the eggs and fry will most likely be eaten by other fish and invertebrates.


The black skirt tetra may be one of the first fish you ever get for your freshwater aquarium. They’re hardy, easy to care for, and make a striking contrast with more colorful fish. As long as you keep them happy in a school with other black skirts, you should get to experience this species for a while in your little ecosystem!

If you have any questions about black skirt tetra care or have experience keeping these fish in your own aquarium, don’t hesitate to leave a comment below!


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