The Brown Ghost Knifefish (Apteronotus leptorhynchus) is a fascinating freshwater fish native to slow-moving rivers and streams in South America. Known for its slender, elongated body and undulating swimming style, it navigates using a weak electric field, which also aids in detecting prey and obstacles. This species is nocturnal and thrives in dimly lit aquariums with plenty of hiding spots like caves, driftwood, and plants.

They require a soft, sandy substrate and water parameters with a slightly acidic to neutral pH (6.5–7.5) and warm temperatures around 75–82°F (24–28°C). Brown Ghost Knifefish are carnivorous and enjoy a diet of live or frozen foods like bloodworms, brine shrimp, and insect larvae. While generally peaceful, they can be territorial with their own species and do best in a species-specific or carefully planned community tank with non-aggressive tankmates. Regular water changes are crucial, as they are sensitive to poor water quality.