studfish

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. Either of two small, brightly colored topminnows (Fundulus catenatus or F. stellifer) of the southeast United States.

Century Dictionary and Cyclopedia

1. n. A kind of killifish, Fundulus (Xenisma) catenatus, 6 or 7 inches long, locally abundant in the Tennessee and Cumberland rivers. It is one of the largest and handsomest of the cyprinodonts. A related species is the spotted studfish, F. (X.) stellifer, of the Alabama river. These represent a section of the genus with the dorsal fin beginning nearly above the anal.

Wiktionary

1. n. Any of several species of small American minnows of the genus Fundulus, such as Fundulus catenatus.

GNU Webster's 1913

1. n. (Zoöl.) Any one of several species of small American minnows of the genus Fundulus, as F. catenatus.