Black Skirt Tetras are one of the fish you’re most likely to come across when you stop into your local fish store and glance into the tanks. Since you’ve likely already seen them, you’ll probably look past them in favor of something more brightly colored. However, this is definitely a mistake.
These fish have a lot to offer both novice and advanced freshwater aquarists. What are Black Skirt Tetras and how do we care for them?
What are Black Skirt Tetras?
Black Skirt Tetras are, like most tetras, South American in origin. Specifically they are found in Argentina, Paraguay and Southern Brazil. While they are definitely tetras they have a very odd body shape compared to more familiar looking fish.
Most Tetras are shaped more like Neon Tetras: slim, cylindrical, “classic fish-shaped.” Black Skirt Tetras are quite a bit chunkier and longer than other Tetras. And while there are long-finned varieties the fins of the wild type are naturally a bit extended. Particularly the anal fin, which the fish use as a communication flag.
For the novice aquarist they are some of the hardiest and least expensive fish you’ll find in the hobby. Black Skirt Tetras have been tank bred for decades and are tolerant of a wide range of water conditions, food items, and tank mates.
They also come in a variety of additional color morphs, including a white leucistic color (often sold as White Skirt Tetras). There is even a genetically modified Glofish variety that has jellyfish and coral DNA transplanted into them. Under an ultraviolet light they fluoresce brilliantly in varying neon shades!
Expert hobbyists will find them to be a subdued in tone yet active tank mate for both small and medium sized fish. Their muted silvery grey color nicely offsets more brilliantly colored fish.
Regardless of the coloration Black Skirt Tetras can find a place in nearly any fish tank. Let’s get into the details on caring for them!
- Common Names: Black Skirt Tetra, Black Widow Tetra, Petticoat Tetra, Butterfly Tetra
- Scientific Name: Gymnocorymbus ternetzi
- Origin: South America
- Length: 2½-3 inches
- Aquarium Size: 15+ Gallons
- Temperament: Peaceful; Schooling
- Ease of Care: Very Easy
Black Skirt Tetra Care
This section covers important Black Skirt Tetra care topics such as aquarium size, feeding, tank mates, and more.
Black Skirt Tetras are usually sold as 1 inch youngsters that are a deep black in color. When small, they can live comfortably in a 10 gallon tank. However you need to be aware that they will grow quite a bit over time.
15 gallons is the absolute minimum with 20 gallons being better since these are also a schooling species. 6 individuals is the least you’ll want with more always being better. When kept in groups of less than 6 fish, Black Skirt Tetras can become a bit nippy, especially towards fish that look similar or have temptingly long fins.
Like most of the older aquarium staple fish, Black Skirt Tetras are extremely hardy and tolerant of a wide range of water conditions. In the wilds of South America, you’d find these fish in slightly acidic to neutral water conditions (pH 6.0-7.0).
They still prefer this range of water chemistry. But they acclimate easily even to hard, alkaline water (pH 7.0+) though they are very unlikely to breed in these conditions. One of the best ways to condition their water is through the addition of plant tannins.
Black Skirt Tetras aren’t blackwater fish like some of their cousins. So they don’t really need or even appreciate heavy doses of liquid plant tannins. But a few pieces of driftwood or some Indian Almond Leaves goes a long way.
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This buffers the water slightly towards acidity and provides a more natural water chemistry for them. Go for Mopani wood or Malaysian driftwood if you’re looking for a steady release of tannins.
Indian Almond leaves are less expensive and take up less space but offer a similar amount of tannins once you add enough. The leaves simply need replacing over time as they decay. Temperature-wise, Black Skirt Tetras thrive from 72-80℉ and can even go a little warmer but this is the ideal range for them.
Plants & Substrate
Live plants and Black Skirt Tetras are a match made in heaven. These fish are entirely plant-safe: they are entirely carnivorous and won’t bother your plants in the slightest. Typically they will alternate between swimming in open water and hovering individually among the plant growth right at the edge of your “forest.”
At feeding time they will likely dart in and out of the plants to feed as they would in the wild! Aquarium plants are fantastic for nearly any setup. Plants remove ammonia, nitrite, and nitrate, processing it into their own fertilizer.
This makes them essentially an extension of your aquarium’s biological filtration capacity! Plants also suck up carbon dioxide, release oxygen, create detritus for bacterial biofilms to accumulate, and provide shelter for your fish. If you think plants are a bit of a bother though, silk plants will also work with Black Skirt Tetras.
As I mentioned earlier, driftwood is also an excellent addition for the tannins it releases. Rocks like Seiryu Stone can be used with ease and provide a nice mineral contrast to the fish and plants. Just make sure that you avoid using types that strongly buffer the water towards alkalinity.
For the substrate you can use either sand or gravel. I recommend a darker substrate to ensure that your fish colors stay strong and contrasting. In aquarium stores Black Skirt Tetras often look washed out.
This is due to the pale gravel, intense lighting, and lack of places to hide. But once you get them home and into a nicely planted tank with a darker substrate you’ll see them color up over the course of a few days!
Tank Mates for Black Skirt Tetras
Black Skirt Tetras are perfectly sized community fish and can be kept with a very wide range of species. They are right on the edge of medium sized yet have tiny mouths and are mostly peaceful.
As a result they can be kept with any fish larger than a nano fish yet isn’t large enough to eat them. And given their deep bodies this means they can be kept with some fairly large fish. Even medium sized Cichlids would have a hard time swallowing a fully grown Black Skirt Tetra, making them excellent dither fish for these tanks.
Other medium sized community fish are the best tank mates for them. Barbs, Livebearers, Gouramis, Dwarf Cichlids and smaller Cichlids like Convicts are all fine choices. They will also get along with any bottom dwelling fish like Corydoras and Plecostomus.
While they are mostly peaceful I need to caution you regarding long finned fish. This includes Bettas, fancy Guppies, Angelfish, and the like. Black Skirt Tetras are unfortunately notorious fin-nippers. They love seeing the wiggling, trailing fins of slower fish and may decide to snap at them.
The best way to mitigate this is to keep them in schools. Most tetras tend to be a bit nippy but they prefer focusing their attention on each other. A group of Black Skirt Tetras will likely have some frayed fins among each other but will likely leave your other fish alone.
I wouldn’t keep them with truly tiny fish, either. Chili Rasboras, Pea Puffer fish and similar nano fish are just too tiny and may get nipped at by them. Dwarf Shrimp are also unfortunately a bad idea. However larger species like Bamboo and full-grown Amano Shrimp will do well with Black Skirt Tetras.
Good Tank Mates for Black Skirt Tetras
- Gouramis, Dwarf & Medium sized Cichlids, Tetras, Livebearers, Barbs, and other small to medium-sized Community fish
- Other Black Skirt Tetras
- Bettas, Angelfish, and other long-finned fish with caution
- Plecos, Corydoras, and other bottom dwellers
- Larger Shrimp & Snails
Poor Tank Mates for Black Skirt Tetras
- Nano fish
- Large, predatory or territorial fish
- Dwarf Shrimp
Feeding Black Skirt Tetras
Black Skirt Tetras are some of the most low maintenance aquarium fish you’ll ever find and that includes feeding them. They have been eating flakes and/or pellets their entire lives and will continue to do so greedily once you bring them home.
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Pellets or flakes can form the bulk of their diet but pellets are slightly better as they don’t fault the water as easily as flakes. Just make sure that you choose the right sized pellets as Black Skirt Tetras have small mouths for such chunky fish.
Also, I always recommend enriching the diets of aquarium fish with other kinds of food. Not only does it spice things up for them but it provides missing nutrients and often boosts their color. Frozen and live foods like brine shrimp, daphnia, tubifex worms, and bloodworms are an excellent way to condition your fish to spawn as well.
In the wild, Black Skirt Tetras are micro predators. This means they naturally eat invertebrates like mosquito larvae, water fleas, fish fry, baby shrimp, worms, and anything else they can find. Replicating this diet is the best way to keep them healthy over the long term!
Breeding Black Skirt Tetras
Tetras in general tend to be a little on the challenging side to breed. Thankfully, Black Skirt Tetras are one of the easiest tetras for beginners to spawn! They are so used to typical aquarium conditions that so long as you try a little to make their conditions cozy they will almost certainly reward you with eggs.
The main challenges are: identifying males versus females, conditioning your tetras, and once they’ve spawned, recovering the eggs and raising the fry. Black Skirt Tetras are on the difficult side to sex. Once they are fully mature and ready to breed it does get a bit easier.
The females will be noticeably plumper once the eggs begin developing inside of them. And sexually mature males tend to self-identify as they will spar with one another and wag their slightly larger anal fins constantly.
Also, females can be as much as ½ inch longer than a male of the same age. The best way to ensure you have a male and female is to simply buy as many of them as you can afford.
Next, we need to condition our Black Skirt Tetras. Many aquarists may get lucky feeding their fish flakes in hard water. But you’re all but guaranteed to have them spawn if you condition them by offering them mostly live and frozen invertebrate-based foods. Especially tubifex worms, which are rich in fat that the female needs for egg production.
Couple this with a slight temperature drop of 3 to 5 degrees and a water level drop of 30-50%, simulating the winter dry season for a month. Then when “spring” arrives, you can refill the water level using either tap water. Or, if you want to go all the way, using distilled or reverse osmosis (RO) water.
The influx of pure water makes the fish think the spring rains have arrived, which is the prime time to spawn. Coupled with the rich food you’ve been feeding, the males should start fighting even harder and the females should begin to swell.
Black Skirt Tetras are egg scatterers. This means that they don’t provide parental care for their eggs or fry. They simply drop them onto the nearest plants, preferably thickly tangled plants like Guppy Grass or Java Moss. Once the eggs are laid the tetras promptly forget about them and go back to their business.
Once it’s clear that they’ve spawned you need to remove either the plants holding the eggs or the parents ASAP. Otherwise your tetras will simply eat them or the newly hatched fry. Black Skirt Tetra eggs hatch in 2-3 days into young fry that lay still on the bottom for another 2-3 days.
After they’ve absorbed their yolk sac the young tetras begin swimming freely. At this point you can offer them a batch of homemade infusoria, which are cultured single celled organisms. That’s how tiny these fish are!
Within a couple of weeks you can switch over to live brine shrimp nauplii, micro worms and powdered flake food. Once they’ve made it this far, you simply need to keep their water clean with regular water changes (fry food tends to foul aquariums quickly) and grow them up until they’re ready for a new home!