The quick, darting movements of the Blackskirt Hifin Tetra defy the delicate nature of its fine, long fins!

The Long Finned Black Tetra was developed from the Black Tetra or Blackskirt TetraGymnocorymbus ternetzi. It is a very durable fish and a great choice for the beginning aquarist. It is known by several names and variations of these names, including Longfin Blackskirt Tetra, Longfinned Black Widow Tetra, Black Hifin Tetra, Blackskirt Hifin Tetra, and Longfin Blackskirt Tetra.

Like its predecessor, the Long Finned Black Tetra is very popular and readily available. This schooling fish will appreciate the company of its own kind. A standard aquarium school is made up of about 6 to 7 fish, but more is even better. This active and fast moving fish does have a tendency towards fin nipping. Because of this, it should not be kept with smaller fishes but will do very well in a community tank with larger fishes.

These fish are are very durable and easy to keep, but they are a bit more difficult to breed than the Blackskirt Tetra, probably because they are highly inbred already. Provide them with a 15 gallon aquarium or larger. They like a well-lit tank with dense areas of bunched low vegetation, leaving lots of open areas for swimming. They are hardy at 70 to 90° F, but are prone to develop ich if kept in colder temperatures.

Other very nice varieties of the Blackskirt Tetra have been developed as well. Some color morphs that offer a unique appearance include the White Tetra or Goldenskirt Tetra, which has become very common, and the Colored Skirt Tetra.

For Information on keeping freshwater fish, see:
Freshwater Aquarium Guide: Aquarium Setup and Care

  • Kingdom: Animalia
  • Phylum: Chordata
  • Class: Actinopterygii
  • Order: Characiformes
  • Family: Characidae
  • Genus: Gymnocorymbus
  • Species: ternetzi
Long Finned Black Tetra – Quick Aquarium Care
  • Aquarist Experience Level: Beginner
  • Size of fish – inches: 2.2 inches (5.51 cm)
  • Minimum Tank Size: 15 gal (57 L)
  • Temperament: Semi-aggressive
  • Aquarium Hardiness: Very Hardy
  • Temperature: 70.0 to 79.0° F (21.1 to 26.1&deg C)
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Habitat: Distribution / Background

The Black Tetra Gymnocorymbus ternetzi was described by Boulenger in 1895. The species is not listed on the IUCN Red List. They are found in South America in Paraguay and Guapore Basins. These fish show a preference for slow-moving streams and tributaries that are dimly lit from dense forest canopies. They inhabit the upper layers of the water, feeding on worms, small crustaceans, and insects. Many are captive-bred for the aquarium industry.

The Long Finned Black Tetra was first developed from the Black Tetra in Europe. There are no wild populations of this variety, but like its predecessor, many are captive-bred for the aquarium industry. Other common names it is known by include Longfin Blackskirt Tetra, Longfinned Black Widow Tetra, Black Hifin Tetra, Blackskirt Hifin Tetra, Longfin Blackskirt Tetra, and various combinations of these.

  • Scientific Name: Gymnocorymbus ternetzi
  • Social Grouping: Groups
  • IUCN Red List: NE – Not Evaluated or not listed


The Long Finned Black Tetra is a deep-bodied and laterally-compressed species. This fish will reach about 2 1/4 inches (5.5 cm) in the home aquarium, but will breed at just 1 1/2 inches. It has a lifespan of about 6 to 7 years. It is distinguished by two vertical stripes and by what appear to be overly-developed dorsal and anal fins. Its fins make it appear as though it has a “skirt,” with most of its mass on the bottom half of its body. The already long fins of its predecessor, the Blackskirt Tetra, were then specifically developed to be extra long and flowing on this tetra. The fine black color changes to gray as it reaches adulthood.

  • Size of fish – inches: 2.2 inches (5.51 cm) – These fish get up to 2 1/4 inches (5.5 cm) but will breed at 1.5 inches.
  • Lifespan: 7 years – They have a lifespan of about 6 to 7 years.

Fish Keeping Difficulty

The Long Finned Black Tetra is a hardy fish that is great for the beginning fish keeper. These fish are mass produced commercially and adapt very well to water condition changes. They make great tankmates for peaceful community aquariums.

  • Aquarium Hardiness: Very Hardy
  • Aquarist Experience Level: Beginner

Foods and Feeding

Since they are omnivorous, the Long Finned Black Tetra will generally eat all kinds of live, fresh, and flake foods. To keep a good balance, give them a high quality flake food every day. Feed brine shrimp (either live or frozen) or blood worms as a treat. These tetras like several feedings a day, but offer only what they can consume in 3 minutes or less at each feeding.

  • Diet Type: Omnivore
  • Flake Food: Yes
  • Tablet / Pellet: Yes
  • Live foods (fishes, shrimps, worms): Some of Diet
  • Vegetable Food: Some of Diet
  • Meaty Food: Some of Diet
  • Feeding Frequency: Several feedings per day

Aquarium Care

The Long Finned Black Tetra is easy to care for provided the water is kept clean. Aquariums are closed systems, and regardless of size, all need some maintenance. Over time, decomposing organic matter, nitrates, and phosphate build up and water hardness increases due to evaporation. To combat these ever-changing conditions, water should be replaced on a regular basis, especially if the tank is densely stocked. At least 25 to 50% of the tank water should be replaced every other week.

  • Water Changes: Bi-weekly

Aquarium Setup

Long Finned Black Tetra are very active swimmers. They need an aquarium that is at least 15 gallons or more, and they will appreciate a soft, peat-filtered water. Although dim lighting and a darker gravel substrate will bring out this tetra’s best coloring, these fish prefer a well-lit tank with some plant cover. They like areas of bunched low vegetation but also need open areas to swim freely. Additionally, the tank should be securely covered as these fish are skilled jumpers and will probably do so if given the opportunity.

A biotype setup is a great choice for this tetra and is very easy to put together. The substrate should be made up of river sand. Provide a few hiding places with some driftwood branches and twisted roots. If driftwood is hard to find, an alternative is common beech that has been dried and stripped of all its bark. Some dried leaves can be added to stain the water a light brown and give the tank a natural feel. Leaves should be removed and replaced every few weeks.

  • Minimum Tank Size: 15 gal (57 L) – A 15-gallon tank is the smallest advisable to host a small school.
  • Suitable for Nano Tank: Yes
  • Substrate Type: Any
  • Lighting Needs: Moderate – normal lighting
  • Temperature: 70.0 to 79.0° F (21.1 to 26.1&deg C)
  • Breeding Temperature: 82.0° F – These fish will spawn at 82 to 86° F (27.8 to 30° C).
  • Range ph: 5.8-8.5
  • Hardness Range: 3 – 30 dGH
  • Brackish: No
  • Water Movement: Moderate
  • Water Region: All – These fish will swim in all areas of the aquarium.

Social Behaviors

These fish are active and can be semi-aggressive fin nippers. They should be kept in a community aquarium with fish the same size or larger. With age, they become a more sedentary fish. To keep fin nipping to a minimum, keep this fish in groups of 6 or more. When kept in groups, the fish focus on each other rather than their tankmates. The best tankmates for this fish are rasboras, danios, other tetras, most livebearers, Corydoras, and some of the peaceful dwarf cichlids.

  • Venomous: No
  • Temperament: Semi-aggressive – Relative to other tetras, Black Skirts have a tendency to be slightly more aggressive, and fin nipping is not uncommon among this species.
  • Compatible with:
    • Same species – conspecifics: Yes
    • Peaceful fish (): Monitor – Watch for stress in other fish caused by fin nipping.
    • Semi-Aggressive (): Threat
    • Aggressive (): Threat
    • Large Semi-Aggressive (): Threat
    • Large Aggressive, Predatory (): Threat
    • Monitor – Tetras can out compete them for food.
    • Shrimps, Crabs, Snails: Safe – not aggressive
    • Plants: Safe

Sex: Sexual differences

The male’s dorsal fin is narrow and more pointed. A mature female is plumper.

Breeding / Reproduction

Long Finned Black Tetras have been bred in captivity. In fact, they are just one of the various strains of the Blackskirt Tetrathat have been developed, along with a number of colored varieties. These egg layers are almost as easily bred as their predecessors provided that they are paired well or kept in groups containing about 6 individuals of each sex.

For the best success, the females should be conditioned separately from the males for 7 to 10 days prior to spawning. Feed them plenty of small, live foods and frozen foods. Provide a planted 10 to 20 gallon breeding tank with a small, air-powered sponge filter for filtration and aeration. The breeding tank should be a few degrees warmer than the main tank, at around 82 to 86° F (27.8 to 30° C), with a pH on the acidic side of neutral, and a water hardiness below 15 dGH. Keep the tank dimly lit with clumps of spawning mops or java moss, so the female has a place to deposit the adhesive eggs. A layer of mesh also works if it is wide enough for eggs to pass through but small enough to keep parents out.

The males will chase the females through the plants, occasionally quivering. The females will lay up to 500 or more eggs in a 2 to 3 hour period. Once a successful spawn has been achieved, remove the parents, or they will eat the eggs. Any eggs that are unfertilized will soon start to look fuzzy as they develop a fungal growth. Remove these eggs to prevent fungus from spreading to the healthy, fertilized eggs. The fertilized eggs will hatch in approximately 18 to 36 hours, and the fry become free-swimming a few days later.

For the first few days, feed the fry infusoria-type foods until they can feed on microworm or brine shrimp nauplii. The biggest challenge is that the young are prone to starving to death if they are in a dark tank and can’t find a food source. The fry should have plenty of light, both day and night, until they are large enough to eat freshly-hatched brine shrimp. See Breeding Freshwater Fish: Characins for a general description of breeding processes, and see Fish Food for Fry for information about types of foods for raising the young.

  • Ease of Breeding: Easy

Fish Diseases

Long Finned Black Tetra are prone to develop ick if kept in colder temperatures. But overall, they are hardy, and disease is not usually a problem in a well-maintained aquarium. That being said, there is no guarantee that you won’t have to deal with health problems or disease. Anything you add to your tank can introduce disease. Not only other fish but plants, substrate, and decorations can harbor bacteria. Take great care and make sure to properly clean or quarantine anything that you add to an established tank so as not to upset the balance.

A good thing about Long Finned Black Tetra is that due to their resilience, an outbreak of disease can often be limited to just one or a few fishes if dealt with at an early stage. When keeping more sensitive types of fish, it is common for all fishes to be infected even before the first warning signs can be noticed. The best way to proactively prevent disease is to give your Flame Tetra the proper environment and a well-balanced diet. The more closely their environment resembles their natural habitat, the less stress the fish will have, making them healthier and happier. Stressed fish are more likely to acquire disease.

As with most fish, they are prone to skin flukes, parasitic infestations (protozoa, worms, etc.), ichthyobodo infection, parasitic infestations (protozoa, worms, etc.), bacterial infections (general), and bacterial disease. Aquarists should read up on common tank diseases. Knowing the signs and catching and treating them early makes a huge difference. For information about freshwater fish diseases and illnesses, see Aquarium Fish Diseases and Treatments.


The Long Finned Black Tetra, also known as the Longfin Blackskirt Tetra and Blackskirt Hifin Tetra, is readily available and inexpensive.