Gymnotus carapo is a robustly-built knifefish from Central and South America. Banded knives reach about 24" in maximum length, but are quite peaceful with fish that will not fit in their mouths. This fish pairs best will large yet peaceful fish, such as certain rainbowfish, Geophagus spp., silver dollars, etc. Take care when dosing medications, as scaleless fish such as these are sensitive to many chemicals, especially those containing copper.
This is a young adult, about 7" long.