Snapping Eels are impudent residents of the Mermaid Kingdom.

They wriggle and dart, threatening to bite fingers and noses. Queen Aquareine once temporarily stiffened them because of their impudence. (The Sea Fairies chapter 6)

Background

The term "snapping eel" is not a formal name or even common slang for any real eel species. The name does appear in other works of popular culture, such as Mass Effect and Kaijudo, all of which postdate the lifetime of L. Frank Baum.