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Black Ghost Knifefish
Please Note: Due to variations within species, your item may not look identical to the image provided. Approximate size range may also vary between individual specimen.
Black Ghost Knifefish (Apteronotus albifrons)
Additional locales and sizes may be available!

Quick Stats

Care Level Moderate
Temperament Semi-aggressive
Color Form Black
Diet Carnivore
Water Conditions 73-80° F, KH 0-10, pH 6.5-7.0
Max. Size 1' 6"
Origin South America
Family Apteronotidae
Minimum Tank Size 150 gallons
Compatibility View Chart
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The Black Ghost Knifefish is a member of the Apteronotidae family and the speckled knifefish group. It is considered a true bony fish. When properly cared for, the Black Ghost Knifefish can reach well over one foot in length. It possesses a weak electrical organ at the caudal peduncles which is used to locate food.

It requires a minimum of a 150 gallon tank with excellent filtration. It is generally timid and reclusive, preferring a fine-gravel-bottom aquarium with plenty of roots and rocks for hiding places, as well as subdued to dark lighting. To better appreciate this fish, many hobbyists will purchase a "ghost tube," a clear plastic tube that facilitates viewing during the day. Once accustomed to its surroundings, the Black Ghost Knifefish can become incredibly tame and trusting to the point of being hand-held. It does well with other, larger species of a peaceful nature, but may be aggressive towards those of similar or smaller size.

Carnivorous, the Black Ghost Knifefish will eat all types of live foods including meat, chopped earthworms, as well as frozen and flaked foods.

Approximate Purchase Size: Small: 1-1/2" to 2"; Medium: 2" to 3-1/2"; Large: 3-1/2" to 5"

Customer Testimonials

Eric H Mountain View , CA
Although large (7-1/2"), my Black Ghost is innocuous, and not the least bit aggressive. As it ages, it becomes friendlier, and even takes food from my hand.
Debbie C Duncan , OK
This fish is a must-have. I have never seen an aggressive side to this fish. Mine will eat from my hand and actually likes for me to place my hand in the water, where he swims up and lies in my hand. It is very entertaining, and really make waves at feeding time.
James W Doylestown , PA
I have been keeping freshwater tropical fish for about 15 years, and the Black Ghost Knifefish is my favorite. I have read several descriptions stating the Ghost Knife can be an aggressive fish, but in my experience that simply isn't true. I currently have a 9" Black Ghost Knifefish in a 150-gallon community aquarium, and he is completely peaceful to even the smallest of Tetras. I wonder if anyone who claims they are aggressive has actually seen them attack and/or eat other fish, or is merely basing that assertion on the "Knifefish" name, since other Knifefish can indeed be very aggressive predators.
Jeffrey A Columbia , SC
I have read that these fish don't like to come out unless the tank is dark. My fish swims happily around the aquarium all day with Congo Tetras, Tiger Barbs, Gouramis, Bala Sharks, etc. It eats out of my hand every time and likes to be "petted" even when I'm not feeding him. Very fun, and easy to care for.
Heather B Newport News , VA
After some consideration, I purchased a Black Ghost Knifefish. This fish is one of the most gentle and beautiful fish I have ever had. The way in which it glides through the water is amazing. It is very peaceful and loves to hide in the tube I placed in the tank. I would definitely recommend this fish to someone who is looking for something unique and has the space for it.
John Partlow , VA
This fish is very nice to the other fish, but hides a lot. It is also easy to care for.
Peggy H Marshfield , WI
I've been learning a lot about these beautiful fish and highly recommend one if you have at least a 30-gallon aquarium and passive tank mates. My Black Ghost Knifefish gets along well with a Horse Loach, a Tiger Pleco, Iran Rainbows, Danios, a Knight Goby, and a Gold Algae Eater. He is my favorite because he has learned to eat out of my fingers and enjoys the tank throughout the day. I have provided various "enclosed spaces" that also allow me to view him.
Ryan M Bellingham , WA
I have four tanks: 180, 120, 55, and 35 gallons. I have two Black Ghost Knives currently. The oldest is my personal friend in all the tanks. I read the posts above and all say they haven't seen angressive side. Mine has ONLY ONCE bitten me by accident, I was cleaning and startled him, IT WAS MY FAULT. But they can get you decently. He does feed by hand and is extremely gentle. Like I said, it was my fault. Get a routine going for touching him and that is the safest way. But he does eat Ghost Shimp live and small guppies. He loves the Ghost Shrimp!! Just feed the shrimp blood worms before feeding them to something. (A boost in nutrients.)
Amber Dawn R Klamath Falls , OR
My Ghost Knifefish is peaceful most of the time but will eat my guppies. He will also eat live earth worms if hand fed.
Bryan G Belleville , IN
I have done a lot of research on this fish. I am so happy because I am finally getting one for my tank!!! Seeing all the comments it seems like this fish is extremely awsome!!!
Benjamin W Richmond
I have a Black ghost knife fish that's about 4" long. It started eating freeze dried blood worms out of my hand in less than a week. It is easily my favorite fish. :)
Jake R Santa Rosa , CA
This fish is the coolest looking fish I have ever had. Its incredibly passive, and is sharing a 55 gallon tank with a Bichir and rainbowfish. They just get friendlier and hide less as they get more comfortable.
Rasheed R Washington DC , WA
After some consideration, I purchased a pair of Black Ghost Knifefish. This fish is one of the most gentle and beautiful fish I have ever had. The way in which it glides through the water is amazing.
Richard R Lansdaler , PA
I have a Black Ghost that is about 6-7 inches and he is quite a sight. He is territorial, though he can't do much damage. He eats quite a lot for his size and is growing very quickly.
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