They are sensitive fish so restrictive on meds! It will eat your neons and your platies danios when it gets bigger anything it can fit in its mouth! And It gets big 20" if I remember correctly!
I took this from a site I found
A full sized Black Ghost Knifefish is a big animal which requires a big home. You will need to eventually provide a tank containing 100 gallons or more if you plan on keeping one of these beauties into adulthood. Providing many hiding places with plants, smooth rocks or aquarium safe wood in a necessity. They are nocturnal and will spend most of the daylight hours hiding in a safe and secure location. Once acclimated to their new home, they should come out of hiding at feeding time. Some have even been taught to feed from their keeper's hand.
Hope this helps