Zebra Knifefish

Zebra Knifefish

Family: Gymnotidae Zebra Knifefish, Gymnotus pedanopterusGymnotus pedanopterusPhoto © Animal-World: Courtesy Ken Childs
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The Zebra Knifefish shows a 'zebra' type patterning along the total length of its body!

The Zebra Knifefish Gymnotus pedanopterus is an incredibly beautiful species of knifefish. It is considered to be very rare and commands a high price when available. This is a more recently recognized fish, described by Mago-Leccia in 1994. The few that have been imported seemed to be hardy and easy to keep.

The Gymnotus genus is a species rich group of electric knifefish. One of the distinguishing characteristics of these fish is the anal fin, which reaches to the very tip of the tail. They also have poor vision, so to accommodate the poor eyesight they have an organ that produces an electric field that will detect objects and movements around it. This helps with navigating and hunting, and it also uses this unique electrical field as a way to communicate with other knife fish.

For years the Banded knifefish G. carapo was the only described species in this group. It was describe by Linnaeus over two centuries ago in 1758. After that time no other species were distinguished until 1994, and then with only 9 species being described. As species were imported, they were usually simply called the Banded Knifefish.

Today, due to dedicated efforts of the Brazilian ichtyologists Ricardo Campos-da-Paz and Flora Fernandes-Matioli, and the Colombian ichthyologist Javier Maldonado-Ocampo, there are currently 32 described species. Fortunately for the aquarist, the absolutely stunning Zebra Knifefish is one of these more recently recognized species. .

Still not much is known about this striking species. Their close relative, the Banded knifefish G. carapo, is a very aggressive fish. So based on that behavior, this species will probably be best kept singly. If you want to try to put them in a community tank, make sure it is large enough to avoid territorial issues. Any other fish needs to be about the same size as the Zebra Knifefish to make sure they do not become food.

The Zebra Knifefish is suggested for aquarists with some fish keeping experience rather than beginner fish keepers. They are very expensive because of their rarity in the fish trade. Their need for pristine waters and the lack of in-depth information about them makes them a challenge. Like most Knife fish they are shy and wild caught so it is sometimes difficult to get them to eat and make it through the first 30 days. Wild caught knifefish often carry parasites as well.

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

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Geographic Distribution
Gymnotus pedanopterus
Data provided by FishBase.org
  • Kingdom: Animalia
  • Phylum: Chordata
  • Class: Actinopterygii
  • Order: Gymnotiformes (Knifefishes)
  • Family: Gymnotidae
  • Genus: Gymnotus
  • Species: pedanopterus
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Zebra Knifefish - Quick Aquarium Care
  • Size of fish - inches: 11.0 inches (27.94 cm)
  • Minimum Tank Size: 55 gal (208 L)
  • Temperament: Semi-aggressive
  • Aquarium Hardiness: Moderately Difficult
  • Temperature: 72.0 to 82.0° F (22.2 to 27.8° C)
  • Aquarist Experience Level: Intermediate
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Habitat: Distribution / Background

The Zebra Knifefish Gymnotus pedanopterus was described by Mago-Leccia in 1994. The are found in South America in the Southern part of Venezuela, including Territorio Amazonas and south of Estado Apure, and also known from tributaries of Rio Negro in Brazil. They have supposedly been found in parts of Peru but these reports are unconfirmed. The species is not listed on the IUCN Red List.

This knife fish lives in slow moving sandy rivers and migrates to flooded black-water forests during the wet season. Its natural habitat is heavily vegetated and normally pretty dark. They will normally inhabit still and sluggish waters. They have been reported in deeper parts of the rivers where they avoid currents. They are a benthic species, inhabiting the bottom of the river and living in the leaf litter and root tangles of river banks. It is a nocturnal predator that feeds on insects, worms, crustaceans, and small fish.

  • Scientific Name: Gymnotus pedanopterus
  • Social Grouping: Unknown
  • IUCN Red List: NE - Not Evaluated or not listed

Description

The Zebra Knifefish is a smaller knife fish species, with 11 inches (28 cm) being the accepted maximum size. Its body is somewhat more rounded than flat. It has small scales and its mouth is turned upwards. It has no dorsal fin but does have an extremely long anal fin starting near the pectoral fin area. This fin can move in an undulating forward or backward motion. The color pattern is 'zebra' like with dark and light clean edged bands extending along the entire length of the body.

This fish also has an electric organ which allows it to generate a very weak electric field around its body. The field helps with a variety of things such as identifying objects in the water, gives it spatial orientation, helps it to navigate, and helps it identify food. Males use an electric 'stereotyped' communication to court females.

  • Size of fish - inches: 11.0 inches (27.94 cm)
  • Lifespan: 15 years - Most knifefish species will have a lifespan of up to 15 years.

Fish Keeping Difficulty

The Zebra Knifefish are suggested for an aquarist with some fish keeping experience due to their the aggressive nature, and the lack of in-depth information for this newer and rare species. They are normally wild caught and can carry parasites. Knifefish are sensitive to some fish medications such as copper and those containing formalin. They are very sensitive to water condition changes as well.

As with many knife fish they are very shy when they are introduced to the tank and it takes time to get them to eat what they need. Being nocturnal by nature makes it even more of an issue, feeding them at night may be necessary.

  • Aquarium Hardiness: Moderately Difficult
  • Aquarist Experience Level: Intermediate

Foods and Feeding

The Zebra Knifefish are carnivores. In the wild they begin to eat when the sun sets and continue throughout the night, feeding on on insects, worms, crustaceans, and small fish. Carapo species like to eat small fish and some may be trained to eat earthworms, bits of frozen/defrosted fish, or high quality flake food.. Feeding knifefish is the most difficult part of caring for them. They are nocturnal and mainly stay at the bottom to feed.

  • Diet Type: Carnivore
  • Flake Food: Occasionally
  • Tablet Pellet: Occasionally
  • Live foods (fishes, shrimps, worms): Most of Diet
  • Meaty Food: All of Diet
  • Feeding Frequency: Daily

Aquarium Care

These fish need good water quality. Weekly 30 - 50% water changes should be done, depending on the bio load. These fish are sensitive to water changes and the water should be tested often to assure that you will have a healthy fish.

  • Water Changes: Weekly - Do a 30 - 50% water change weekly.

Aquarium Setup

The Zebra Knifefish will usually spend their time at or near the bottom of the tank. A large well planted tank with hiding places among rocks and drift wood along with open sandy areas for swimming and feeding are needed. These are one of the smaller knife fish but still need a good sized tank. A 55 gallon (208 l) tank is about as small as you would want to use, but as they mature they will need a larger sized tank, not measuring less then 50 inches in length and !00 gallons. Use a high quality filter but keep the water current low.

Rock structures and plants with long twisted roots make a great decor and offer hiding places for your knife Fish. But these fish do need a good amount of unobstructed swimming room as well. Clay flower pots make great caves for these fish so they have a safe place to take refuge. Some aquarists will use a clear tube for knifefish to hide in. This makes it feel secure, but also the aquarist can see it. Soft sand is the best choice for substrate.

The Zebra Knifefish are nocturnal fish and appreciate subdued lighting with floating plants to break up any light. To get the most enjoyment out of this fish add some Moonlight LED lights to make viewing this fish easier as they will hide when normal tank lights are on.

  • Minimum Tank Size: 55 gal (208 L) - A 55 gallon (208 l) tank is about as small as you would want to use, but as they mature they will need a larger sized tank, not measuring less then 50 inches in length and !00 gallons.
  • Suitable for Nano Tank: No
  • Substrate Type: Sand/Gravel Mix
  • Lighting Needs: Low - subdued lighting
  • Temperature: 72.0 to 82.0° F (22.2 to 27.8° C)
  • Range ph: 6.0-7.0
  • Hardness Range: 2 - 12 dGH
  • Brackish: No
  • Water Movement: Weak
  • Water Region: Bottom - The Zebra Knifefish will usually spend their time at or near the bottom of the tank.

Social Behaviors

Any small fish in the tank will become a meal. They are reported to do fine in large tanks with similar sized fish. Take care to not add aggressive or boisterous fish to the tank as they will likely cause stress to the knifefish and make them withdraw and stop eating. These fish are extremely territorial with their own kind and would need a massive tank to make sure they have their own territory.

  • Venomous: No
  • Temperament: Semi-aggressive
  • Compatible with:
    • Same species - conspecifics: Sometimes - They are extremely territorial with their own kind unless kept in a very large tank with their own territories.
    • Peaceful fish (): Monitor - This fish will eat anything small enough to be considered a meal.
    • Semi-Aggressive (): Threat
    • Aggressive (): Threat
    • Large Semi-Aggressive (): Threat
    • Large Aggressive, Predatory (): Threat
    • Slow Swimmers & Eaters (): Monitor
    • Shrimps, Crabs, Snails: May be aggressive - Knifefish hunt at night for worms, crustaceans, insects and snails.
    • Plants: Safe

Sex: Sexual differences

Sexual differences are unknown.

Breeding / Reproduction

It has not been bred in captivity.

  • Ease of Breeding: Unknown

Fish Diseases

The biggest issue with most knifefish is starvation and sickness caused by lack of nutrition. These fish 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. Knifefish are sensitive to some fish medications such as copper and those containing formalin.

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. Make sure to quarantine live food before feeding.

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 fish 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. A stressed fish is more likely to acquire disease.

As with most fish the Zebra Knifefish 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.

Availability

The Zebra Knifefish is very rare.

References

Author: Ken Childs, Clarice Brough CFS, Jeremy Roche
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Lastest Animal Stories on Zebra Knifefish


Anonymous - 2008-09-11
I like this web site. It is pretty cool and cool for my kids to look at. It has cats and dogs, fish, and if you do not know this web site, look it up!

  • kye turnbull - 2013-04-12
    how do they see this comment and dont know this website?
  • Clarice Brough - 2013-04-17
    Thanks for the kudos! We work hard to provide good info, and it's nice to hear your voice about it:)
Reply
amanda - 2012-11-24
I really love this guy...I already have the black ghost and the zebra will be added to my collection ...

Reply
Mark - 2010-11-12
Can an African brown knifefish coexist with a black ghost knifefish?

  • samiran roy,india - 2011-09-02
    Yes, they can can, but only if you have a large enough tank and plenty of hiding places for the two and also at the same time, be ready for squabbles because the black gf can be fiesty.
  • E.J. - 2011-09-08
    Most definitely they can. I have Ghost Knifes, African Knifes, Clown Knifes, and another brown type of Knife with a yellow streak down its back, that I am unsure of the name, all living in the same 55 gallon tank. They seem to all get along well except for the Clowns, now that they are getting larger they have become more aggressive so I will be putting them into their own tank soon.
Reply
leonard - 2010-11-16
I got 2 big fish tanks, 350 gal with too wolffish, a jack demsey, about 3 others in there too, & 75 gal wide, that holds my gymnotus knifefish or banned fish, I kinda wanna put knifefish in the big tank but I think my wolffish will kill it.

Reply