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Black Ghost Knifefish

Black Ghost Knife Fish

Family: Apteronotidae (Ghost Knife Fishes) Black Ghost KnifefishApteronotus albifronsPhoto © Animal-World: Courtesy Ken Childs

  The popular Black Ghost Knifefish is readily distinguished from other knife fish by the white and black banded area just in front of tail fin!

   The Black Ghost Knifefish received its unusual name because of a rumor that some tribes in the Amazon jungle believe that the souls of the dead inhabit this fish. No one can substantiate this information and it may just be a story created by the people collecting the fish, but it's a good story.

   For good reason, the Black Ghost Knifefish is the most well known species of knifefish in the aquarium industry. One reason for this is that they have been imported for decades. Other reasons include being unusual, interesting and amazingly beautiful. Until a few years ago, all offered for sale were wild caught and had been imported from South America, mainly from Brazil. The good news is that they are now being bred in Indonesia by the thousands, so much of the pressure has been taken off the wild populations. Odds are that if you see an individual of 5 inches or more offered of sale, it was collected in the wild. Specimens smaller than 5 inches were most likely produced in and imported from Indonesia.

For more Information on keeping freshwater fish see:
Guide to a Happy, Healthy Freshwater Aquarium

Habitat: Distribution / Background

   The Black Ghost Knifefish was described by Linnaeus in 1766. Black Ghosts are found in South America throughout much of the Amazon River and its tributaries. It is nocturnal and preys on insect larvae.

• Scientific Name: Apteronotus albifrons
• Social Grouping: Solitary
• IUCN Red List: NE - Not Evaluated or not listed - The species is not listed on the IUCN Red List.

Description

   The black body of the Black Ghost Knifefish is flat and elongated. It has a continuous fin along the underside formed by a joining of the caudal and anal fin and moves with an undulating motion. Although they appear clumsy, they have a built in ‘radar' system that uses low voltage electricity to help them navigate. This and their undulating lower fin allow them to gracefully move forwards and backwards through the aquarium.

• Maximum Size: 20.0 inches (50.80 cm)

Fish Keeping Difficulty

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

Foods and Feeding

   The Black Ghost Knifefish are carnivores. In the wild they are nocturnal, when the sun sets and throughout the night they feed on insect larvae. In the aquarium this is a fish hat prefers fresh or fresh frozen foods such as bloodworms, brine shrimp or blackworms.
   A full sized Black Ghost Knifefish is a big animal which requires a big home. You will need to eventually provide a tank containing 100 gallons or more if you plan on keeping one of these beauties into adulthood. Providing many hiding places with plants, smooth rocks or aquarium safe wood in a necessity. They are nocturnal and will spend most of the daylight hours hiding in a safe and secure location. Once acclimated to their new home, they should come out of hiding at feeding time. Some have even been taught to feed from their keeper's hand.

• Diet Type: Carnivore
• Flake Food: No
• Tablet Pellet: Yes
• Live foods (fishes, shrimps, worms): Most of Diet
• Meaty Food: All of Diet
• Feeding Frequency: Daily

Aquarium Care

• Water Changes: Monthly

Aquarium Setup

• Minimum Tank Size: 100 gal (379 L)
• Suitable for Nano Tank: No
• Substrate Type: Any
• Lighting Needs: Low - subdued lighting
• Temperature: 73.0 - 82.0° F (22.8 - 27.8° C)
• Range ph: 8.0-6.0
• Hardness Range: 5 - 19 dGH
• Brackish: No
• Water Movement: Weak
• Water Region: Bottom

Social Behaviors

   Black Ghosts can become aggressive with members of their own species and members of other, similar species. Other than that, they are usually quite timid. They do have a large mouth so small fish or invertebrates kept in the same tank may eventually become a meal for a hungry Black Ghost.

• Venomous: No
• Temperament: Semi-aggressive
• Same species - conspecifics: Yes
• Peaceful fish (): Monitor - While it is not necessarily aggressive, it will eat anything small enough to be considered a meal.
• Shrimps, Crabs, Snails: Threat - is aggressive - In the wild, this fish hunts at night for worms, crustaceans, insects and snails.
• Plants: Safe

Sex: Sexual differences

   Sexual differences are unknown.

Breeding / Reproduction

   This species is being bred commercially in Indonesia but the method used is unknown. There are hobbyists that claim to have successfully bred the Black Ghost Knifefish in an aquarium but they seem reluctant to share the details. There is some information on this subject, scattered reports, but there is nothing yet documented from reputable sources so it will not be reproduced here. One thing for certain is that if you want to give it a try, you'll need a big aquarium, probably containing 100 gallons or more.

• Ease of Breeding: Difficult

Availability

  Now that they are being bred in captivity, the Black Ghost Knifefish are available all year long. Large specimens may command a high price, mainly due to the higher costs of shipping them. Smaller specimens are quite affordable.

References

Animal-World References
Freshwater Fish and Plants Tropical Fish ~ Freshwater Fish ~ Aquatic Plants

Author: Ken Childs

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Lastest Comments on Black Ghost Knife Fish View all 41 comments on Black Ghost Knife Fish Add Your Comment

Gina - 2012-05-10 I have bought 2 bgkf and I have a 125 gallon tank. Both fish have died within a day of me buying them. I have 2 red tips a black shark and a rainbow shark. My water always tests fine pH is 7.0. I am confused and disappointed. I don't know what's causing the fish to die. Any help would be nice. Jeremy Roche - 2012-05-11 Could be the place you got them from. How did you acclimate them to the tank? They stress very easy so a slow acclimation is best. Anonymous - 2012-05-11 I allowed the bag to float for 15 minutes and than released them into the tank. They were active and found a hiding place. Next morning they were fine and a couple hrs later they died. Reply

katelyn hampton - 2012-02-11 I have recently bought a BGK and I have been trying to feed it blood worms,brine shrimp, and mysis shrimp. I have not seen it eat anything and I am concerned that it is not eating please reply soon. Charlie Roche - 2012-02-11 Your little guy is probably just fine. It takes them a couple of days to aclimate to new surroundings. Alex Burleson - 2012-02-11 It is not uncommon for them to not eat during the first few days that they're adjusting to their environment. Continue to feed the fish, and eventually, he should eat. Additionally, Knifefish, tend to be more nocturnal. Feed the fish, with the lights off. Collecting Clownfish - 2012-02-14 Those are SO cool! I do know that the only time I remember having success with them, was when there were not too many bottom feeders to compete, no aggressive tank mate, and larger water changes. They like their water 6.0 to 8.0 pH, but more importantly, the stability of this pH, and the cleanliness of the water quality. They are very sensitive to any water quality changes for the bad. I have read 40% to 50% every two weeks being the optimum in keeping this eventually 20' long fish alive. If your tank is very well established, there may be foods in the substrate he is eating. Look at his sides and see if they are thinning. Getting LIVE black worms or blood worms that wiggle may be what he needs as far as getting a feeding response. BGK can be funny in that they suddenly change their personality even IF feeding at first, so don't take it personally. You may want to check your water parameters, look and see what other fish are possibly scaring your BGK and look at his sides to see if he may be eating while you are sleeping. Otherwise, enjoy your cool fish! katelyn hampton - 2012-02-14 Thank-you for responding so quick I do feed him in the dark I have had him for a little over a week Jeremy Roche - 2012-02-17 Try some Tibifax worms. Sometimes in an overfed tank the Knife with will eat off the bottom while you sleep. If the Knife is maintaining size it is probably just shy. May just be a trial and error on that it likes to eat. Any aggressive fish in the tank with it? Water testing should be done as well to make sure that isn't putting extra stress on it. Kay - 2012-03-19 I have two and they are so Awesome! - They are extremely active. The one I had in the past never came out during the day, but these are constantly showing themselves. They love the frozen Plankton best, but do enjoy the blood worms. They are probably one of the coolest fish I have had the pleasure of caring for. Reply

Brittany - 2012-02-10 I was thinking about getting a BGKF, but I have 4 Dojo Loachs, and 3 Bala Sharks. Does anyone know if this would be a bad idea or do you think they would be alright? I dont want anyone of them to get killed. Clarice Brough - 2012-02-16 The Black Ghost Knife is an awesome fish. They can get aggressive with their own species, and other knifefish. But would probably be okay with the Dojo's and Bala Sharks in a large enough aquarium. Both the Black Ghost and the Bala Sharks get very big, so 100 gallons minimum to start and then you'll need a larger tank as they grow. Reply

samiran roy,india - 2011-11-04 I have a BGK which i bought when it was about 2 inches long.now a after a six month period it has grown to around 7 and a half inches and has consumed lots of pellet food in the process. Reply

Chad H. - 2010-09-13 I have a 55 gallon aquarium that houses 2 Clown Loaches, 3 Tiger Barbs, 1 Pleco, 1 Khulli Loach, & 1 Blind Cave Tetra. I am fascinated by the Black Ghost Knife fish....would it be a good addition to my tank? I have 3 caves for hiding space and will add more if needed. jake - 2011-10-12 Be careful with the tiger barbs. I have 3 in my tank (plus other fish). I put in 2 bgkf, one of which didn't have all the white on its tail, just a white tip which the tiger barbs bit whenever it was out..... sadly it died not long after. In saying that however, the other bgkf is doing extreammally well! Reply

david - 2011-06-12 Can I keep an Apteronotus albifrons in a 55 gallon aquarium with 2x Geophagus steindachneri and 3x Metynnis argenteus? Charlie Roche - 2011-06-13 Nope-sorry. The Knifefish needs a minimum of 100 gallon tank on his own. They can be agressive and they do get huge and if it fits in their mouth, they will attempt to eat it. samiran roy,india - 2011-09-02 If the BGK is about 2 inches, it can be kept, but you should have a future planning for the fish because they get to be 40 cm or more. Reply

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