Considered a synonym of Poecilia mexicana Steindachner, 1863
- Poeser, Fred. 2003. "Geographic variation in Poecilia Bloch and Schneider, 1801 (Teleostei: Poeciliidae) with descriptions of three new species and lectotypes for P. dovii Günther, 1866 and for P. vandepolli van Lidth de Jeude, 1887". From the Amazon R. to the Amazon molly and back again. The evolution and systematics of the genus Poecilia Bloch and Schneider, 1801. 44-69 (ffm00012) (abstract)
Original description as Gambusia modesta:
- Müller, J.W. von. 1864. "Reisen in den Vereinigten Staaten, Canada und Mexico. 3 vols". F. A. Brockhaus, Leipzig, 1864-65. 1-3:1-394, 1-482, 1-482 (ffm04587)