I bought two 10" Ossa Knifefish (Rhamphichthys rostratus) recently for around 16 bucks each. One is deffinately more active than the other. Today I fed the fish right after I turned off the aquarium light and the larger, more active ossa knife fish came alive and started swimming around the tank looking for food. I've always loved hand feeding fish so I pinched some live blackworms and stuck my hand right in front of it, less cautiously than I normally would as I didn't expect it to be ready to be hand fed anyway. To my surprise, the knife fish was not startled at all and began eating vigorously out of my hand! It was an amazing experience and hopefully next time, if there is a next time, I can record a video and post it.