Freshwater Fish

Black Tetra (Gymnocorymbus Ternetzi) Care Guide

The Black Skirt Tetra is an excellent addition to a community aquarium of peaceful freshwater fish.

Although these fish lack the bright, vibrant colors of some of the other popular tetra species, their darker striped appearance can work well in a dramatic monochrome setting. And it is the dark, shadowy color of the fish that gives it another common name; the Black Widow Tetra.

Read this guide to learn how to care for the beautiful and enigmatic Black Skirt Tetra.

TETRA Black Skirt – Overview

Scientific name: Gymnocorymbus Ternetzi
Common name (species) Black Tetra Skirt, Black Widow Tetra, Petticoat Tetra, Blackamoor
Family Characidae
Source It is found in South America, including the Paraguay River basin, Argentina, and Brazil.
Diet Omnivore
level of care Easy
Exercise Active fish in schools
Life expectancy 3 to 5 years
Temper Calm
tank level Swims in all areas of the water column, but mostly in the middle.
Minimum tank size 15 gallons
Temperature range Tropical 70° to 85° Fahrenheit
Hardness of water 4-8 dKH
pH range 6.0 to 7.5
Filtration / Flow Rate Prefers moderate flow with excellent filtration.
type of water Sweet water
Breeding Egg layer, moderately easy to breed
Compatibility Species of peaceful communities
OK, for planted tanks? insurance with plants


The Black Skirt Tetra was first described in 1895 by Boulenger.

These attractive tetras are widely distributed in South America, specifically in the Paraguay and Guapore river basins, Argentina and Brazil. These fish are not currently listed on the IUCN Red List, as their numbers in the wild are abundant and most specimens found for sale in fish stores are captive bred.

Natural habitat

In the wild, the Black Skirt Tetra inhabits the upper areas of the water column, typically found in small streams, creeks, and river tributaries, where the water is slow-moving and well shaded by overhanging trees.

The fish are omnivorous and feed on plant matter, small crustaceans, insects and worms.


Black skirted tetras have the characteristic tetra body shape, being taller at the front of their body, but the rear tapers markedly towards the tail.

The unusual shape of the fish is enhanced by the shape of its fins. The dorsal fin is small and square, while the caudal fin is forked and thin. But what is most striking is the anal fin, which extends from the center of the fish’s body to the caudal and thickens in the belly of the fish.


The Black Skirt Tetra has a silver-gray, almost translucent body. The color fades to almost black in the middle of the body and there are two vertical black bands on the front of the body.

The fins are typically black or charcoal gray, being translucent with very small rays.

Boys or girls?

Although both sexes look largely the same, female Black Skirt Tetras are usually slightly larger than males and are plumper when in breeding condition.

Males often have a broader anal fin than females.

other varieties

You can also find a long finned variety of these fish called the Black Skirt Hifin Tetra or Longfin Black Skirt Tetra which was developed in Europe.

Other developments in the species include naturally colored strains that appear blue, white, and pink, all of which can be found quite easily, either at fish stores or online. However, there are also some artificially dyed variants, which we do not recommend for ethical reasons.


A mature Black Skirt Tetra is about 3 inches long.

Life expectancy

Black skirt tetras live between 3 and 5 years in captivity, although some have reportedly lived longer than that.

Activity level / temperament

Black Skirt Tetras are active shoals that are generally very peaceful characters.

The only downside to the fish is its typical tetra habit of nipping fins.

Compatibility and tankmates

These are schools of fish, so I recommend keeping a group of at least five individuals or more if you have a large setup. The fish will be more confident in the safety of numbers and will likely have a longer lifespan and better health.

tank mates

Aggressive fish should be avoided, as should nippy fish that might be attracted to the Black Skirt Tetras’ long fins. On the other hand, you should avoid adding fish with long, pendulous fins to your community that could be targeted by black skirt tetras.

Suitable tankmates for these fish could include:

  • corydora catfish
  • harlequin rasbora
  • rasbora chili
  • Danio Celestial Pearl
  • dwarf gourami
  • Bolivian ram


All species of fish do best when fed a high quality, balanced and nutritious diet.

Don’t waste your hard-earned money on cheap fish food! Although that huge tub of flakes may seem like a good value, the food is most likely packaged with a filler that contains no nutritional value.

What to feed your black skirt tetras

Black skirt tetras are omnivores, meaning they eat both plant matter and meaty protein.

In the wild, these fish eat insects, bugs, tiny crustaceans, worms, and some vegetation. In the captive environment, these are not picky eaters, happily consuming tropical fish flakes, pellets, frozen bloodworms, daphnia, brine shrimp and the like.

Although your fish will appreciate the addition of some live food to its diet as a treat, you should remove the food from the liquid it comes in as it can contain bacteria and parasites.

For the same reason, you should never take live food from the environment ! Instead, we recommend that you use frozen meaty protein foods.

How much and how often to feed

Feed your Black Skirt Tetras two to three times a day.

Just give your fish what it will eat in a few minutes. Be careful not to overfeed your fish. Uneaten food will sink into the substrate, where it will gradually break down and contaminate the water.

tank requirements

tank size

I recommend a 15 gallon tank size for a small school of Black Skirt Tetras, although larger is better if possible.

If you plan to keep a community of different species, a 20-gallon tank is a better option. That provides plenty of room for these active fish to swim and reduces the risk of overcrowding the fish, which can stress them out and create health problems.

As these are live, active fish, a long tank provides more swimming space than a tall one and provides a larger surface area for valuable gas exchange to take place, helping to oxygenate the water.

These tetras can jump, so a sliding lid or well-fitting lid for your aquarium is essential.

Tank Configuration


Black Skirt Tetras have no specific requirements when it comes to the substrate. However, a dark substrate reproduces the fish’s natural environment where the ground is covered with leaf litter.

A sandy substrate or river gravel work well.


These fish adapt to a natural-looking habitat, so use driftwood, rocks, and twisted roots to create an attractive aquascape, but be sure to leave plenty of room for swimming.

In the wild, the fish live in a blackwater environment, where the water is colored a light brown by fallen leaves that fall from the canopy above. You can add some dry leaves to the tank to recreate that look.

Low lighting helps to show Black Skirt Tetra’s coloring to best effect.

Live plants look good and help keep the environment healthy by absorbing nitrates and CO2 from the water and giving off oxygen as part of the process of photosynthesis.

habitat requirements


These fish need clean, safe water in which to thrive, so an efficient and well-maintained filtration system is a must.

In the wild, the water these tetras live in moves slowly, so take care to redirect or dampen the flow, using plants or decorations.

water parameters

water temperature

Black skirt tetras are tropical fish that need a water temperature between 70° and 85°F, ideally in the middle of that range.

pH range and water hardness

Aquarium water should have a pH between 6.0 and 7.5, with a water hardness of 4 to 8 dKH.

Turning on

Black Skirt Tetras like relatively dim lighting, so choose an LED lighting unit that you can adjust to suit your needs, and select plants that will grow in dim lighting conditions.

tank maintenance

In addition to installing an efficient filtration unit, you should do partial weekly water changes of at least 30% to keep nitrate levels low.

As part of your water change routine, vacuum the substrate, under décor items, in the corners of the tank, and around plants to remove uneaten food, fish waste, and decaying plant material.

Use an algae magnet to clean the viewing panels, but try not to remove the bacteria and biofilm that form an essential part of your biofilter setup.

About once a month, rinse the filter media with dirty tank water and replace it as needed, per the manufacturer’s guidelines.

aquarium setup

Lay out everything you need to set up the aquarium, including:

  • Dark river sand or gravel substrate
  • LED lighting unit
  • HOB Filtration System
  • water conditioner
  • Heater
  • aquarium thermometer
  • Twisted roots, smooth rocks, driftwood
  • dried almond leaves
  • Floors

How to set up your aquarium

  1. Wash off the dust from the substrate with running water.
  2. Add two to three inches of sand or gravel to your fish tank. Place a container upside down on the substrate.
  3. Install the filter and heater, but do not turn them on yet.
  4. Add non-chlorinated tap water to the tank, pouring the water slowly over the upturned container so the gravel does not spread.
  5. It is essential that the water contains a small amount of ammonia to trigger the nitrogen cycle in the biological filter media. So, you must “seed” the water. Do this by adding a handful of gravel from a mature aquarium, a few pinches of fish food, or a drop or two of pure ammonia.
  6. Rinse the dust off your chosen tank decorations and place them in your tank.
  7. If you are using live plants, cut off broken or dead leaves and stems. Give the plants enough space between each stem so they have a chance to grow and spread.
  8. Turn on your heater and filter. Live plants need light to photosynthesize, so turn on the lighting unit for eight to 10 hours every day.

You must now wait for the aquarium to “cycle” before adding any fish. That time allows nitrifying bacteria to colonize biological filter media and surfaces within the tank. Test the water every other day until ammonia and nitrite levels are zero and nitrates are below 20 ppm.

If necessary, allow more time for the process.

Health and sickness

As long as you feed your fish correctly, keep the tank clean, and maintain the filter media, Black Skirt Tetras are pretty hardy fish.

signs of good health

These fish are active creatures that must swim in all areas of the tank, spending much of their time on sandbanks.

red flags

Here are some red flags that could indicate possible health conditions, including:

  • loss of appetite
  • Inactivity
  • Not studying with tankmates
  • Ulcers, sores, or red spots on the skin.
  • Hitting or rubbing against gravel or tank decorations

Common health problems and treatment

Health problem Symptoms or causes suggested action
Ich (white spot disease) Ich is caused by a parasite called Ichthyophthirius multifiliis.
White spot fish float against tank decorations. Within a few days, a scattering of white spots appears on the gills, body, and fins.
Increase the water temperature to 82o F for three days. Use Ich medication to treat the water.
Flukes Flukes are parasites that attach to the gills or body of infected fish. Fish will secrete excess body mucus and rub against tank decorations. Treat the water with an antiparasitic treatment.
fungal infections White cotton-like growths on the head and body. Quarantine infected fish. Treat with antifungal medications.
Bacterial infections Skin ulcers, sores, red areas, torn and bloody fins. Treat the water with antibacterial drugs.


Black Skirt Tetras are egg layers.

Set up a 10-gallon spawning tank, including a spawning mop, and line the bottom of the tank with fine-gauge netting to prevent fish from eating the eggs.

Pick a couple of healthy fish and add them to the spawning tank. Give the fish live foods that are high in protein so that the pair is in breeding condition. The female will drop up to 1,000 eggs, scattering them throughout the tank. The eggs sink to the bottom of the aquarium, falling through the net where they are out of reach of the adults.

When spawning is complete, return the adults to the main aquarium.

The eggs will hatch after 24 to 36 hours. The fry feed from the egg sac for the first few days, after which you can feed them infusoria or fry foods. In a week or two, the fry will be large enough to eat small brine shrimp.


You can buy Black Skirt Tetras at most fish stores for a few dollars a fish. Natural colored variants can usually be purchased online and are slightly more expensive.

product recommendations

  • water conditioner / dechlorinator
  • algae magnet
  • aquarium thermometer
  • aquarium vacuum cleaner
  • Books on tropical fish farming
  • Filtration system
  • Aquarium (minimum size 15 gallons)
  • Heater
  • High quality tropical fish flakes, pellets, frozen foods
  • LED lighting unit
  • Floors
  • Smooth stones, driftwood, twisted roots
  • Sand or dark gravel substrate

In conclusion

I hope you have enjoyed our care guide for the beautiful Black Skirt Tetra.

These calm, active, easy-care fish make a wonderful addition to a community tank. Do you have Black Widows in your setup? What tankmates have you chosen for them? Tell us in the comment box below!

And remember to share our guide if you liked it.

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