The Brown Knife Fish is an aquarium classic. Found in Brazil, Peru and the Guianas, the Brown Knife was described by Ellis in 1912 as the Apteronotus leptorhynchus . As is common for most knifefish, the body is elongated without a dorsal fin and has one long anal fin that is used to propel the knifefish through the water, often in reverse as fast as forward. Using a weak electrical field to help navigate at night (and in murky water), the Brown Knife does best as the sole knifefish in the aquarium, unless introduced simultaneously. In the aquarium it will require many hiding places and will immediately claim any long caves. (Hide a PVC pipe under other rocks to make a knife-house.) This knife will eat most meaty foods, chopped worms, sinking pellets and even some flake foods, though it is initially a shy eater and will take time to adapt to aquarium feeding. As its name implies, the Brown Knifefish has a brown body with a slightly transparent anal fin and can reach a length of 15”, though aquarium specimens are usually 5 to 8 inches in length. The knife should be treated as a smooth skin fish when treating for parasite infestations. Safe with other docile fish, make sure the Brown Knife has a good hiding place and is an active eater.
Brown Knifefish (Ellis, 1912)
Scientific Name Apteronotus leptorhynchus
Alt. Common Name Brown Knife, Leptorhyncus Knife
Origin Brazil, Peru, Guinea
Aquarist Level Intermediate
Community Aquarium Safe No
Coloration brown body with a long transparent anal fin, no dorsal fin
Same Species Compatibility best kept singly
Inter-Species Compatibility med-lg "community" fish
Captive Size 6-10"
Wild Size 15"
Minimum Recommended Aquarium Size 50
Sexual Dimorphism no differences have been noted
Notes: nocturnal, prefers dense planting or caves, weak electrical "sonar" used to navigate
I use to take care of some. Out of all the frozen foods, they loved bloodworms. They'd come up to the turkey baster and eat straight from it, they're so cool! The water temperature would be the same as any other tropical fish. They're not hard to take care of. And I've never seem them be aggressive with another fish.
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