Nannostomus grandis is a freshwater species of fish belonging to the characin family Lebiasinidae.

[1] This species is closely related to Nannostomus beckfordi, being somewhat similar in coloration, but with a more elongated body.

It has been described[citation needed] as the largest member of the genus; however, N. harrisoni consistently reaches a mature length in excess of 60 mm and is the more likely claimant for that distinction.

It was only recently formally described by Zarske,[2] although the author reports it probably had been assumed to be a form of N. beckfordi in the past and had even been exported for the aquarium trade at times.

It is native to Brazil and currently has no accepted common name.