Black Skirt Tetra (Gymnocorymbus ternetzi): Care Guide


Common Name(s)Black Skirt Tetra, Petticoat Tetra, Blackamoor, Black Widow Tetra
Scientific NameGymnocorymbus ternetzi
OriginSouth America
Temperature70–85°F (21-29°C)
Size2-3 inches
Minimum Tank Size15 gallons
Food & DietOmnivorous diet
LifespanUp to 5 years
Water pH6.0-7.5
Tank MatesNeon Tetra, Bolivian Ram, Angelfish, Molly, Guppies, Dwarf Gourami
BreedingEgg scattering spawner
DiseaseMay be susceptible to Ich, bacterial diseases, protozoa infections, and flukes.
Black Skirt Tetra
Black Skirt Tetra (Gymnocorymbus ternetzi)

Black Skirt Tetras (Gymnocorymbus ternetzi) are a species of freshwater fish native to the waters of South America. Within South America, they’re commonly found in bodies of water in Argentina, Brazil, Bolivia, and the Paraguay and Guapore River basins. Black skirt tetras can go by several different names, and some of them are Petticoat Tetra, Blackamoor, and Black Widow Tetra.

Unlike their relatives, Black Skirt Tetras aren’t exactly colorful fish. Towards the front of their body, they have a silver coloration. Towards the back of their body and anal fin, they have a darker coloration. This dark color in the anal fin, also referred to as the “skirt,” tends to fade as they mature. While they do not have bright colors on their body, they are beautiful fish and remain just as popular as other tetras.

Some fishkeepers are attracted to Black Skirt Tetras because it resembles miniature Piranhas. They have a deep body shape, have an underbite, and school in groups. In fact, tetras as distant relatives to Piranhas. However, they are not aggressive fish like Piranhas. While they may occasionally nip at other long-finned fish, they are peaceful community fish.

Their relatively small size, peaceful temperature, and ease of care makes them a great choice for aquarists of various levels.

Black Skirt Tetra Care

Black Skirt Tetras are relatively easy to care for since they do not require complicated aquarium setups. A basic aquarium setup is usually all that is required for these fish, similar to many other tetras.

As schooling fish, they find comfort in numbers. Therefore, a tank setup that accommodates for the group of fish is important. A minimum of 5 Black Skirt Tetras should be kept together, but more fish would be better. A fish may venture away from the group to investigate their surroundings, but they always return. They like to constantly explore the rocks, driftwoods, caves, and plants in the aquarium.

Black Skirt Tetra Temperature

Black Skirt Tetras should be kept in water temperatures ranging between 70–85°F (21-29°C). They originate from warm tropical rivers of South America, and this temperature range would replicate their native habitat.

Since most people do not live in environments with warm temperatures year-round, it is important to install an aquarium heater. The aquarium heater will help warm the water, and stabilize the temperature as well. In an aquarium without a heater, the water temperature can fluctuate rapidly. This would be very stressful for the fish, even if the temperature remained in the optimum temperature range. Therefore, installing an aquarium heater is important.

Black Skirt Tetra pH

Black Skirt Tetras should be kept in an aquarium with a water pH of 6.0-7.5. While the water pH may not be the first thing that comes to mind when keeping fish, it is important. After all, this is the water that the fish lives in. Keeping the water pH at this range will keep the fish healthy. Water pH should be monitored regularly, since changes in the pH can be deadly for the fish. If slight changes in the pH level is detected, it may indicate an issue that can be addressed before it becomes more serious.

Black Skirt Tetra Size

Black Skirt Tetras are relatively small fish, and they only grow to about 2-3 inches in size at full maturity. Not all fish grow to the same size, since there are various factors that contribute to their growth. This includes genetics and and their environment. A fish with good genes can still have stunted growth if they are not fed well or they live in poorly maintained environments. In order to allow the fish to grow to their full potential, it is important to feed a varied diet and provide regular maintenance.

Long-finned Black Skirt Tetras may reach over 3 inches in size, since their long fins are included in the measurement.

Black Skirt Tetra Tank Size

Black Skirt Tetras require a minimum tank size of 15 gallons. While they aren’t large fish, these schooling fish must be kept in a group of 5 or more fish. Therefore, a 15 gallon tank would be required to accommodate for these fish. Of course, a larger group would require a larger aquarium tank.

Providing adequate tank space for Black Skirt Tetras is important because they are active fish. They also like to swim and explore rocks, driftwoods, caves, and plants. Therefore, the aquarium tank should be big enough for the fish to swim in, even after adding all of the hardscape and plants.

How many Black Skirt Tetras can you keep in a 10 gallon tank?

If you apply the general rule of thumb of “1 inch of fish per gallon of water,” you can keep approximately 3 Black Skirt Tetras in a 10 gallon aquarium. However, this rule is only a general guideline that does not always apply. In fact, keeping Black Skirt Tetras in a 10 gallon tank is not recommended.

At 10 gallons, there would not be enough space for the fish to swim, explore, and exhibit their natural behaviors. In addition, a group of only 3 fish would be considered too small. Since they are a schooling fish, a minimum of 5 or more Black Skirt Tetras is recommended. If there isn’t enough fish in the group, they will feel stressed. This may result in timid behavior, as well as washed-out colors.

Black Skirt Tetra Food and Diet

Black skirt tetras aren’t known to be picky, quite the opposite, actually. They’ve been known to eat anything, including aquarium plants. In their native environment, black skirt tetras are known to feed on insects such as mosquito larvae, small invertebrates, and worms. A good feeding schedule would be to provide your black skirt tetras flakes or pellets daily. You can also feed them live foods such as brine shrimp or bloodworms. Be careful of overfeeding your fish; overfeeding can lead to constipation and other serious illnesses.

Black Skirt Tetra Lifespan

Black Skirt Tetra has a lifespan of up to 5 years. However, their lifespan can be drastically shortened due to environmental factors. This includes, water parameters such as pH and nitrate levels. Providing a balanced diet is important as well. Lastly, if they are placed under constant stress, this can shorten their lifespan as well. They will feel stressed if there are larger fish that are constantly harassing them. Even without larger fish in the tank, if there aren’t enough fish in the group, they may feel vulnerable and stressed.

Black Skirt Tetra Tank Setup

A tank setup for Black Skirt Tetras should consist of the following:

  • Aquarium Tank (at least 15 gallons)
  • Aquarium Heater
  • Aquarium Filter
  • Aquarium Light
  • Hardscape (Driftwood, Rocks, and Caves)
  • Live Aquarium Plants

While the hardscape and live plants are optional, this can play a significant role in the well-being of the fish. In their native habitat, Black Skirt Tetras do not always swim in open waters. In fact, most of their time is spent among rocks, driftwood, and thick vegetation. They swim through the crevices of these structures and plants in search of food, but it also helps them from becoming food to other larger fish as well. They are aware that there are predators in the waters, which is why they are schooling fish. In a bare tank, they may feel like they are always in open water, making them feel vulnerable.

Black Skirt Tetra Fish – 55 Gallon Planted Aquarium Rescaped

Black Skirt Tetra Breeding

Breeding Black Skirt Tetras is not difficult, but there is a method to follow and patience is required.

In order to breed Black Skirt Tetras, a separate breeding tank is required. The purpose of the breeding tank is to isolate the breeding pair since they are shy fish and will not breed when there are other fish in the same tank. Another purpose of the breeding tank is to prevent as much eggs from getting eaten after spawning.

The breeding tank should be a minimum of 10 gallons, and it should be set up with same water as the main tank. The bottom of the breeding tank should be filled with Java Moss. This would allow the eggs to fall through the thick growth, and help prevent the parents from eating the eggs after spawning. Alternatives to Java Moss would be artificial grass, divider net, or spawning mop.

Once the breeding tank is set up, add the breeding pair into the tank. In order to choose a breeding pair, a male and female fish must be selected. You can identify if a Black Skirt Tetras is a male or female by their body shape. Male Black Skirt Tetras have a skinnier and longer body, while female Black Skirt Tetras have a shorter and plumper body. The females will become plump especially when they are full of eggs. In addition, males may have a white dot on their caudal fins. The males usually have anal fins that bend back towards the tail as well.

After then breeding pair is identified and placed in the breeding tank, they must be conditioned to breed. High-protein diet and live fish food would help condition the breeding pair.

A well-conditioned female would be very plump. Technically, Black Skirt Tetras can not become pregnant because they are not livebearers. However, you can tell if the female is carrying eggs by observing the abdomen. When they are carrying eggs, it should be significantly more full, and the eggs can be seen in the bag-like pocket on the fish. In addition, the dark spot would be visible as well. This is located in the abdomen of the fish, towards to the tail.

If the breeding pair is well-conditioned and they are comfortable, they male fish will start to chase the female around. At this stage, they should be observed and monitored as much as possible, without disturbing them. If the male is chasing the female too aggressively and it is causing harm to the female, the pair may need to be separated. If the spawn is successful, the female can lay up to 1000 eggs. The eggs would be scattered throughout the entire tank.

After a spawn and fertilized, the parents will try to eat the eggs. Therefore, it is important to remove the parents from the breeding tank as soon as possible. The Java Moss placed on the bottom of the tank will give you more time to remove the parents before all of the eggs are eaten.

After a spawn, Black Skirt Tetras eggs will hatch in 24-36 hours. Compared to eggs of many other fish species, which may take multiple days or even weeks to hatch, this is considered relatively quick. Since Black Skirt Tetra eggs hatch quickly, it is very important to remove the parents from the breeding tank as soon as possible. Black Skirt Tetras will eat the fry, and once they hatch in the same tank as the parents, they will have very little chance of surviving. While the eggs may have been protected underneath the Java Moss or spawning mop, hatched fry will cling onto the aquarium wall. This makes them an easy target, and significantly reduce their chance of survival.

Black Skirt Tetra fry will not be very active for the first few days after hatching. They will not be feeding either, since all of the nutrient that they need is in their attached egg sac. However, after few days, they will start feeding on infusoria and other fry food. In a couple of weeks, they will be able to consume baby brine shrimp. After a month, they will be able to start feeding on crushed dry flake food.

Black Skirt Tetra Disease

While Black Skirt Tetra are hardy fish, they aren’t immune to diseases. Some diseases that may affect Black Skirt Tetra include Ich, bacterial diseases, protozoa infections, and flukes.

Ich (Ichthyophthirius multifiliis) is a disease that is very common disease among Black Skirt Tetra, as well as many other tetra species. Symptoms include white spots (up to 1mm in diameter) on the body and fins, hence the common name, “white spot disease.” In addition to the white spots, the behavior of the fish may change as well. They may experience a loss of appetite, increased breathing rate, flashing (scratching its body against objects), among many others. The symptoms are often quite obvious, especially during the later stages of the disease. If the disease is recognized early on, the fish may be treatable. However, it is always better to prevent the disease by proper fishkeeping techniques and regular maintenance.

There are various bacterial diseases that may affect Black Skirt Tetras, and one of the most common type is fin rot. Fish that are affected may have rotting fins, loss of appetite, and loss of energy. Fin rot is often caused by poor water conditions. There may be an imbalance in the water pH, ammonia, or nitrate level. If the issue is detected early on, simply improving the water quality may help the fish recover. There are medications that are available for treating fin rot as well. Medications that may be used for fin rot include Melafix, Myxazin, and Maracyn.

Protozoa infections that may affect Black Skirt Tetra include Velvet disease. The parasite that causes Velvet disease is Oodinium limneticum and Oodiunium pilularis. Affected fish will show symptoms such as yellow dust-like particles on the fish, clamped fins, and lethargy. Fish may be treated with sodium chloride and other medication designed to specifically combat this disease. Slightly increasing the water temperature may help as well.

Black Skirt Tetra may be suffer from flukes (Gyrodactylus sp.), which is a disease caused by parasites. These parasites will invade the skin and gills of the fish, and suck on its blood and body fluids. This will weaken the fish, causing it to loose color, breathe heavily and have clamped fins. It may cause the fish to have blood spots on its fins and body as well. Flukes can be treated with Praziquantel.

Medication and treatment is available for many of the disease. Therefore, if the disease is detected early on, the fish will have a greater chance of recovery. However, even if the fish is able to recover, the treatment process and the disease itself will cause a lot of stress to the fish. Therefore, preventing the disease with proper care and maintenance is important.

Black Skirt Tetra Tank Mates

Tank mates for Black Skirt Tetra should be selected after considering several different factors. This includes their temperament, behavior, and needs regarding the water parameters. Fortunately, since Black Skirt Tetra relatively hardy and peaceful fish, there are many fish that are compatible as tank mates.

Before adding tank mates to the aquarium, make sure there is enough space. If the tank is no larger than a 15 gallon tank, it may be better to keep it a species only tank. Considering that Black Skirt Tetra should be kept in group of 5 or more, it does not leave much space for other tank mates in a small aquarium.

Are Black Skirt Tetra Aggressive?

Black Skirt Tetra are not an aggressive fish, but they are known to be occasional fin nippers. When placed in the tank with other fish with long fins, they may nip at it from time to time. Therefore, it is best to avoid these fish. This is interesting because Black Skirt Tetra have long anal fins themselves, and they are often victims to other fin nippers. This is especially true for long finned variety of Black Skirt Tetras.

Besides their occasional fin nipping behavior, Black Skirt Tetra are peaceful fish. While they may resemble miniature Piranhas in appearance, they do not exhibit the same aggressive behavior. They usually school in groups and will not bother others.

Compatible Tank Mates for Black Skirt Tetra

As a community fish, there’s a lot of fish that are compatible as tank mates for Black Skirt Tetras. Here’s a few examples:

Black Skirt Tetra

The most compatible companion for Black Skirt Tetras are other Black Skirt Tetras. Since they are schooling fish, they like to be around their own species. They will swim and explore their environment as a group. A minimum of 5 Black Skirt Tetras should be kept together, and the more the better. If there is less than 5 fish in the group, they will feel vulnerable and stressed. Without the group, they will not be able to exhibit their natural behavior either. Even with proper care, they may not live as long as they should if they aren’t in a group.

Neon Tetra

Neon Tetras and Black Skirt Tetras are compatible as tank mates. As tetras, they originate from the same family and they are very similar. They have similar needs in terms of their water parameters. They also behave quite similarly, although Black Skirt Tetra tends to be slightly more active. Out of the many possible tank mates, Neon Tetras can be considered to be one of the most compatible candidate.

Guppy

Guppies and Black Skirt Tetra are compatible as tank mates. They are both peaceful fish of similar size. They have similar tank requirements as well. Keep in mind that the Black Skirt Tetras will try to eat the guppy fry, but this is expected since the guppy themselves will prey on their own fry.

Molly

Mollies and Black Skirt Tetra are compatible as tank mates, since they are both peaceful community fish. Mollies aren’t schooling fish, but they are shoaling fish that enjoy the company of other Mollies. Therefore, if Mollies and Black Skirt Tetras are placed in the same tank, the tank should be large enough to accommodate a certain number of both fish species.

Gourami

Gourami and Black Skirt Tetras may be compatible as tank mates. Both fish have similar tank requirements, and both fish are generally peaceful. However, there are many species of Gourami, and some grow to a very large size, close to two feet in length. While the larger species should be avoided, smaller species such as the Dwarf Gourami can be good tank mates for Black Skirt Tetras.

Bolivian Ram

Bolivian Rams and Black Skirt Tetra are compatible as tank mates. Bolivian Rams are one of the most peaceful species of cichlids. As their name suggests, they are native to the tropical waters of Bolivia. Their tanks should be around 72–79°F and have a pH level of 6.0 to 7.5. These water parameters would make them compatible with Black Skirt Tetras. Lastly, both fish grow to around the same size, which is about 3 inches at full maturity.

Angelfish

Angelfish and Black Skirt Tetras are generally compatible as tank mates. While Angelfish may eat smaller species of tetras, Black Skirt Tetras aren’t small enough to get eaten by them. The contrast between the two fish can bring the tank together.

Many aquarists keep Angelfish and Black Skirt Tetras in the same tank successfully. However, keep in mind that some Angelfish have exceptionally long fins. Therefore, the Black Skirt Tetras may nip at their fins occasionally. Since each fish behave differently, it is important to monitor the fish and how they interact.

Shrimp

Shrimps and Black Skirt Tetras are generally compatible as tank mates. While the Black Skirt Tetra will be actively swimming throughout the mid-section of the aquarium, the shrimps will roam the bottom portion of the aquarium. Therefore, they will not be bothering each other very much. However, if the shrimp is very small, it may become prey to the Black Skirt Tetra.

There are many different species of freshwater shrimp that can be kept in aquariums, but Amano Shrimps are one of the most popular species. Amano Shrimps and Black Skirt Tetras are very compatible as tank mates. However, as with other shrimp species, the juvenile shrimps may get eaten by Black Skirt Tetras if they are very small.

Incompatible Tank Mates for Black Skirt Tetra

Black Skirt Tetra are small peaceful fish, but they aren’t compatible with all fish. While they aren’t aggressive fish, they may nip at fish with long fins. These fish should be avoided. In addition, since they are small fish, they can be victims to other aggressive or larger fish. These fish should be avoided as well.

Here’s a few examples of incompatible tank mates for Black Skirt Tetras:

Betta

Betta fish and Black Skirt Tetra are not compatible as tank mates. Since Betta fish have long fins, Black Skirt Tetras may nip at it. In addition, Betta fish can be aggressive as well. Whether the Betta fish become to the fin nipping or it fights back aggressively, there is a chance that a hostile environment will be created. It would be better to avoid this combination.

Cichlids

Cichlids and Black Skirt Tetra are often incompatible. Many species of cichlids are aggressive and significantly larger than Black Skirt Tetras. When placed in the same tank, Black Skirt Tetras may become victims to harassment. Of course, there are compatible cichlid species, such as the Bolivian Rams. However, the majority of cichlids would be incompatible with Black Skirt Tetras.

Oscars

Oscar fish and Black Skirt Tetras are not compatible as tank mates. Similar to many other species of cichlids, Oscar fish are aggressive fish that grow to a large size. In fact, they grow up to 16 inches in size. If both fish are placed in the same tank, Black Skirt Tetras would be eaten very quickly.

Goldfish

Goldfish and Black Skirt Tetra are not recommended as tank mates for a few reasons. First, many goldfish kept as pets have long fins. Therefore, the goldfish can be nipped by the Black Skirt Tetra. Second, goldfish and Black Skirt Tetras have different temperature requirements. Goldfish are cold water fish and Black Skirt Tetras live in warmer tropical waters. Since both fish are generally hardy, it is possible to find a temperature where both fish can survive. However, this would result in a compromised habitat for both fish. Lastly, it is very likely that the goldfish will outgrow the tank. Goldfish are known to grown over a foot long. Even if the goldfish didn’t eat the Black Skirt Tetra, they will be producing a lot of waste at this size. It would be very difficult to create a environment that would accommodate both fish long term.

Where to find Black Skirt Tetra for Sale

Since Black Skirt Tetras have been a popular fish in the aquarium hobby for many years, they are readily available in local fish stores. In fact, big box retailers such as Petco and Petsmart will likely carry them. Of course, they are available from many online retailers as well.

Regarding the price of Black Skirt Tetras, they are not very expensive. They are usually available for $2 to $3 USD per fish. It is rare to see them for sale above $5 USD. While they aren’t expensive, keep in mind that you will usually be purchasing a group of at least 5 of them or more.

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With decades of collective fishkeeping experience, we are happy to share the fish care tips that we've picked up along the way. Our goal at Fish Laboratory is to keep publishing accurate content to help fishkeepers keep their fish and aquarium healthy.

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