Keeping a Ghost Knife (Black Ghost Knifefish) involves providing a large, dimly lit tank with plenty of hiding spots, soft substrate, and excellent water quality, feeding a meaty diet, and ensuring tank mates are too large to be prey, as they grow big (up to 20 inches) and are nocturnal predators sensitive to poor conditions. They need space, hiding caves (driftwood, PVC), and stable, warm water (22-26°F), but are generally peaceful with appropriate tank mates, though they can be aggressive with their own kind in small tanks.