Orthosternarchus tamandua. Beautiful, graceful knifefish. I've seen one swimming with a chili red, and pearl rays...complements your fish collection very nicely. What are you feeding it, and what does it eat? I heard they are hard to feed because of their tiny mouth. I had many chances of getting that knifefish, but was always hesitant because of the feeding nature of this fish. I also think it is nocturnal? Not sure though.
j/k it beautiful tho