Nannostomus marginatus

{{Short description|Species of fish}}

{{DISPLAYTITLE:Nannostomus marginatus}}

{{Speciesbox

| name = Dwarf pencilfish

| image = Nannostomus marginatus.jpg

| status = LC

| status_system = IUCN3.1

| status_ref = {{cite iucn |author=Salvador, G.N. |year=2023 |title=Nannostomus marginatus |volume=2023 |page=e.T49830593A159923479 |doi=10.2305/IUCN.UK.2023-1.RLTS.T49830593A159923479.en |access-date=26 March 2025}}

| taxon = Nannostomus marginatus

| authority = (C. H. Eigenmann, 1909)

}}

Nannostomus marginatus, (from the Greek: nanos = small, and the Latin stomus = relating to the mouth; from the Latin: marginatus = marginated),{{cite book|title=Exotic Aquarium Fishes|author=Dr. William T. Innes|publisher= Innes Publishing Co|location= Philadelphia|year= 1935}}{{cite web|url=https://etyfish.org/lebiasinidae/ |title=Family LEBIASINIDAE Gill 1889 (Pencilfishes)|publisher=Christopher Scharpf and Kenneth J. Lazara|date=13 November 2024|website=The Etyfish Project|accessdate=26 March 2025}} commonly known as the dwarf pencilfish, is a freshwater species of fish belonging to the genus Nannostomus in the characin family Lebiasinidae.{{ITIS |id=163106 |taxon= Nannostomus marginatus |accessdate=Feb 25, 2012 }} They were first described in 1909 by C. H. Eigenmann and are typical of members of this genus being small, elongated fish with prominent horizontal stripes. The most notable feature of N. marginatus is its size, it being one of the smallest members of the genus, only reaching a maximum size of {{cvt|35|mm}}. They occur widely on the South American continent having been recorded in Brazil, Guyana, Colombia, Suriname, and Peru, and have been a popular aquarium species since their introduction to aquarists in the early twentieth century. {{FishBase |Nannostomus|marginatus |month=February|year=2012}}