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Long Finned Black Tetra

Longfin Blackskirt Tetra, Long Finned Black Widow, Black Hifin Tetra

Family: Characidae Long Finned Black Tetra, Gymnocorymbus ternetzi, Long Finned Black Widow Tetra, Blackskirt Hifin Tetra,Gymnocorymbus ternetziPhoto © Animal-World: Courtesy David Brough
Latest Reader Comment - See More
OMG I could not believe my eyes this morning we have a Baby highfin...I have a pair of adults for over a year. Never realized that they were male and female. My new... (more)  Ann

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

The Long Finned Black Tetra is a very commonly available fish. This tetra is a strain of fish developed from the Black Tetra or Blackskirt Tetra Gymnocorymbus ternetzi. It is a very durable fish and makes a very good fish for the beginner. 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 also very popular and is readily available. Being a schooling fish they will appreciate the company of their own kind, a standard aquarium school is made up of about 6 - 7 fish, and more is even better. It is very active and fast moving, but 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. This is probably because of their being 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, which leaves lots of open areas for swimming. They are hardy at 70 - 90° F, but are prone to develop ick if kept in colder temperatures.

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

Geographic Distribution
Gymnocorymbus ternetzi
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  • Kingdom: Animalia
  • Phylum: Chordata
  • Class: Actinopterygii
  • Order: Characiformes
  • Family: Characidae
  • Genus: Gymnocorymbus
  • Species: ternetzi
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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° 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, normally 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. Today many are captive bred for the aquarium industry. There are no wild populations of this captive bred variety. 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 same terms.

  • 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 species and laterally compressed. 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 - 7 years. It is distinguished by two vertical stripes and by what appears to be overly developed dorsal and anal fins. These make it appear as if though it has a "skirt", with most of its mass on the bottom half of the body. These already long fins have been specifically developed to the extreme on the Long Finned Black Tetra variety to be extra long and flowing. The fine black color changes to a gray in the adult.

  • 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 life span of about 6 - 7 years.

Fish Keeping Difficulty

The Long Finned Black Tetra is a hardy fish that is great for the beginner fish keeper. These fish are mass produced commercially, and adapt very well to water condition changes. They make great tank mates 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 everyday. 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 on size all need some maintenance. Over time decomposing organic matter, nitrates, and phosphate build up and the 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 - 50% of the tank water should be replaced every other week.

  • Water Changes: Bi-weekly

Aquarium Setup

The Long Finned Black Tetra are very active swimmers. They need an aquarium that is at least 15 gallons or more and like a soft, peat-filtered water. Although dim lighting and a darker gravel substrate will bring out the tetras best coloring, these fish prefer a well-lit tank with some plant cover. They do 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 few hiding places with some driftwood branches and twisted roots. If driftwood is hard to get an alternative is common beech once dried and stripped of all its bark. Some dried leaves can be added which will stain the water a light brown and give them a natural feel. Leaves should be removed and replaced every few weeks.

  • Minimum Tank Size: 15 gal (57 L) - Fifteen gallons is the least amount of space 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° 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

They 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 being a fin nipper 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
    • Slow Swimmers & Eaters (): Monitor
    • Shrimps, Crabs, Snails: Safe - not aggressive
    • Plants: Safe

Sex: Sexual differences

The male's dorsal fin is more narrowed and more pointed. A mature female is also more plump.

Breeding / Reproduction

The Long Finned Black Tetra are egg layers. They are easily breed with a good pairing. 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. . For a description of breeding characin fish, see Breeding Freshwater Fish: Characins.

  • Ease of Breeding: Easy

Fish Diseases

The 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 bring disease to your tank. 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 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 you deal with it 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 give them a well balanced diet. The closer to their natural habitat the less stress the fish will have, making them healthier and happy. 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. It is recommended to read up on the 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 or Longfin Blackskirt Tetra is readily available and is inexpensive.


Author: Clarice Brough CFS, Jeremy Roche
Lastest Animal Stories on Long Finned Black Tetra

Ann - 2015-07-04
OMG I could not believe my eyes this morning we have a Baby highfin...I have a pair of adults for over a year. Never realized that they were male and female. My new little fellow is going to be called Ralph and he is only half as big as my pinky fingernail. Too Cute !!

  • Clarice Brough - 2015-07-09
    Very cool... and congratulations! Would love to see some pictures.
FishNewbie - 2009-03-08
I just bought 2 of these guys. For some reason, they have been harrassing my Mickey Mouse Platy even though they are the same size. My poor platy has been chased all day by both of the fish :( I hope they calm down

  • jackie b - 2014-02-20
    Get rid of one of your fish the platy will die soon. Cant believe some aquarists don't do research of platies. These are HIGHLY Aggressive so keep them with Discus and oscars
  • Nikki Hobbs - 2014-08-27
    I also have in my tank 2 Long Finned Black Tetras, One Mickey Mouse Platy. However I also have in the same tank a Head and Tail Light Tetra, Ghost Shrimp and a Plecostomus. My tank is only 14 gallons but I'm having absolutely no problems with them I have had them for a few years now. Honestly my tank is flurishing phenomenally. The key is having enough structures and plants for your fish to hide and find territories of their own. Try to rearange the tank when introducing new fish as to allow all the fish to find new territories at once so they don't over take each others and cause chaos. Hope this helps!
Chadwick Mcconnell - 2013-07-09
I have 5 hi fin black Tetra's in a 20 gallon long tank.  They have used this tank as their home for almost a year now.  I am adding some albino cory Catfish and a snail today.  I hope they will get along with one another.

Alysia yvonne polk - 2012-11-04
I have 3 short skirts and 1 long skirt and they are wonderful to watch and they do great with my 3 big silverdollars, but they did eat a baby mollie i had, im only 14 and i love fish and i say everyone should have some of these fish:)