Gymnotus choco, commonly known as the cuchillo (Spanish for "knife"), is an electric knifefish. G. choco is distinguished from its cogenerate species group by a color pattern possessing pale yellow bands oriented obliquely, wherein the interband margins are wavy or even irregular; one to three Y-shaped dark bands occur on its body's posterior section; and its pale bands do not extend above the fish's lateral line on its body's anterior two-thirds. G. choco is most similar to G. paraguensis from the Pantanal in Brazil and Paraguay. From the latter, it is distinguished by having a narrower mouth, a more cylindrical body, and a longer preanal distance.