Fundulus is a genus of ray-finned fishes in the superfamily Funduloidea, family Fundulidae (of which it is the type genus). It belongs to the order of toothcarps (Cyprinodontiformes), and therein the large suborder Cyprinodontoidei. Most of its closest living relatives are egg-laying, with the notable exception of the splitfin livebearers (Goodeidae).

Fundulus catenatus.jpg
Northern studfish (F. catenatus)
Scientific classification e
Kingdom: Animalia
Phylum: Chordata
Class: Actinopterygii
Order: Cyprinodontiformes
Family: Fundulidae
Genus: Fundulus
Lacépède, 1803
Type species
Fundulus mudfish
Lacepède, 1803[1]

See text

They are usually smallish; most species reaching a length of at most 4 in (10 cm) when fully grown. However, a few larger species exist, with the giant killifish (F. grandissimus) and the northern studfish (F. catenatus) growing to twice the genus' average size.

Many of the 40-odd species are commonly known by the highly ambiguous name "killifish" (the general term for egg-laying toothcarps), or the somewhat less ambiguous "topminnow" (a catch-all term for Fundulidae). "Studfish" is a quite unequivocal vernacular name applied to some other Fundulus species; it is not usually used to refer to the genus as a whole, however.

Fundulus have evolved to occupy a wide range of aquatic ecosystems, including marine, estuarine, and freshwater, making it a good comparative model system for studying evolutionary divergence between marine and freshwater environments.[2] To assist with this research, Oxford Nanopore long-read reference genomes have been sequenced for F. xenicus, F. catenatus, F. nottii, and F. olivaceus[3].


Russetfin Topminnow (F. escambiae)

There are currently 39 recognized species in this genus:[4]

Formerly placed in Fundulus were the closely related diamond killifish (Adinia xenica) and the somewhat more distantly related Cuban killifish (Cubanichthys cubensis, a pupfish).


  1. ^ Eschmeyer, William N.; Fricke, Ron & van der Laan, Richard (eds.). "Fundulus". Catalog of Fishes. California Academy of Sciences. Retrieved 23 September 2019.
  2. ^ Burnett, Karen G.; Bain, Lisa J.; Baldwin, William S.; Callard, Gloria V.; Cohen, Sarah; Di Giulio, Richard T.; Evans, David H.; Gómez-Chiarri, Marta; Hahn, Mark E.; Hoover, Cindi A.; Karchner, Sibel I. (2007-12-01). "Fundulus as the premier teleost model in environmental biology: Opportunities for new insights using genomics". Comparative Biochemistry and Physiology Part D: Genomics and Proteomics. 2 (4): 257–286. doi:10.1016/j.cbd.2007.09.001. ISSN 1744-117X. PMC 2128618. PMID 18071578.
  3. ^ Johnson, Lisa K.; Sahasrabudhe, Ruta; Gill, James Anthony; Roach, Jennifer L.; Froenicke, Lutz; Brown, C. Titus; Whitehead, Andrew (2020-06-01). "Draft genome assemblies using sequencing reads from Oxford Nanopore Technology and Illumina platforms for four species of North American Fundulus killifish". GigaScience. 9 (6). doi:10.1093/gigascience/giaa067. PMC 7301629. PMID 32556169.
  4. ^ Froese, Rainer and Pauly, Daniel, eds. (2012). Species of Fundulus in FishBase. August 2012 version.