whats the ideal setting for a knife fish?

Answer 1

A fairly large aquarium, depending on the species of knifefish you get. The smallest of the species sold for aquariums is about 7 inches long as an adult, but others can get to as much as 4 feet!

All should have lots of wood and plants, with dim lighting. They don't have the best eyesight, since they are mostly nocturnal, so to see them active, you may need to use dim light (or purchase actinic bulbs for a "blue" nighttime effect) or use plants and driftwood (this can even be mounted to the brace in the center of a large tank to resemble a root in the water) to provide shade.

Answer 2

an aquarium