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Fish Bio: Black Ghost Knife Fish

The Black Ghost Knife Fish (APTERONOTUS ALBIFRONS) hails from the Amazon River basin in South America. They are one of the most interesting tropical fish to watch due to their strange features.

In the aquarium, Black Ghost Knife Fish are known for their flowing movement and their unique body shape. They are similar to a graceful, rippling black curtain as they swim through an aquarium. You might also notice that their eyes are very beady, and they do not resemble “normal” tropical fish eyeballs. This is due to the fact that Black Ghost Knife Fish have a difficult time seeing.

In fact, Black Ghost Knife Fish have developed electrical organs that allow them to send out electric pulses to navigate through water. Aquarists should avoid placing other fish species that use similar electric navigation and Black Ghost Knifes together because their electrical pulses will interfere with each other confusing themselves in the aquarium.


Black Ghost Knife Fish
Black Ghost Knife Fish


Otherwise, Black Ghost Knife Fish are very peaceful to other tropical fish in the aquarium, and they make great centerpieces for community tanks. That is, if the fish aren’t small enough to fit inside of their mouths. The Black Ghost Knife Fish are gargantuan beasts that grow up to 20? (50 cm), and they should not be placed with smaller tetras or community fish because the Black Ghost Knife Fish will eat them. Not out of maliciousness, but they are small, moving objects that fit in the mouth; the fish doesn’t know better. Speaking of their large size, they should not be kept in tanks less than 75 gallons. Although their maximum size is 20?, they usually do not get to be this big in aquariums, and the average size in aquariums is just over a foot (12?+).



Other water parameters that factor in the well-being of the Black Ghost Knife Fish are pH and temperature. The pH that can accommodate this fish is pretty forgiving, and it ranges from 6.0 to 8.0 (from slightly acidic to neutral to slightly alkaline).

The temperature this fish can be kept at is forgiving as well, 76ºF to 82ºF (24-28°C). It can cover an array of water qualities, but this doesn’t mean the fish is necessarily hardy.

The nitrites and ammonia should always read 0 ppm for this fish, and the nitrate should never rise too high.


Black Ghost Knife Fish
Black Ghost Knife Fish


When one first introduces a Black Ghost Knife Fish into an aquarium, the result can be pretty disappointing for the owner. They have been known to hide behind aquarium decorations, but owners should not remove the decorations in order to view their fish because it will only stress them out even more. They should be given time to adjust to their new environment which can take up to a couple of weeks. One idea is to use a large, plastic, see-through bottle that will allow the Black Ghost Knife Fish to enter and feel safe but still allow its owner to watch him from outside of the glass. Another way is to increase the amount of hiding places, and lower the lighting in the tank.

But after the Black Ghost Knife is accustomed to his tank, it can develop a strong relationship with its owners. Black Ghost Knife Fish owners are known to hand feed their Black Ghost Knife Fish beef heart  Additionally, owners are able to pet and stroke the fish, and the fish will actually run through its owner’s hands. A real interspecies relationship!



Besides beef heart, Black Ghost Knife Fish can accept frozen bloodworm’s, shrimp pellets, brine shrimp, tubifex worms



Owners should be careful when medicating their fish tanks with Black Ghost Knife Fish inside. Since the fish are scale-less  they react differently to medication than fish with scales. They are more sensitive, so the doses of medication should be halved as to not endanger the Black Ghost Knife Fish.

Did you know?!: Black ghost knife fish can swim both backwards just as well as they can swim forwards! They are usually very expensive to purchase but worth every penny!

About Mike

Web designer, football fan and budding traveller.

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