Nannostomus marilynae, (from the Greek: nanos = small, and the Latin stomus = relating to the mouth; marilynae = in honor of ichthyologist, Marilyn Weitzman),[1] commonly known as Marilyn's or greenstripe pencilfish, is a freshwater species of fish belonging to the characin family Lebiasinidae.[2] They have been recorded from the Rio Negro and Rio Orinoco regions of Brazil, Venezuela, and Colombia.[3]