Carl Henry Eigenmann (March 9, 1863 – April 24, 1927) was a German-American ichthyologist of the late nineteenth and early twentieth centuries, who, along with his wife Rosa Smith Eigenmann, and his zoology students is credited with identifying and describing for the first time 195 genera containing nearly 600 species of fishes of North America and South America.

He also studied South American fish collections at Harvard University for a year in 1887–1888, before beginning his career as a researcher and educator in California.

[5] "A review of the genera and species of Diodontidae found in American waters", the first of many papers that Eigenmann authored on his own, was published in the Annals of the New York Academy of Science in 1886, when he was twenty-three years old.

Adele Rosa (Eigenmann) Eiler (1896–1978) accompanied her father on the Irwin Expedition to South America in 1918–19 and received a medical degree from Indiana University in 1921.

[10] In 1887, shortly after their marriage, the Eigenmanns went to Harvard University, where they spent a year studying the collections of fishes[2] made by Louis Agassiz and Franz Steindachner, and produced the first of a series of joint publications.

The results of the Eigenmanns' research at the Museum of Comparative Zoology in Cambridge, Massachusetts, were published in a series of joint publications, including their first report on South American fishes, a precursor to their major work that would follow several years later.

In 1890–92, famed scientist Albert C. L. G. Günther financed Eigenmann's first expedition for the British Museum to western North America.

[2][18] Subsequent explorations focused on the blind vertebrates, including cave fishes and salamanders, found in Indiana, Kentucky, Texas, Missouri, and Cuba.

[19] After a trip to the University of Freiburg in 1906–07, Eigenmann was named the first dean of the IU graduate school in 1908, and retained the post until his death in 1927.

He convinced William Jacob Holland with the Carnegie Museum to sponsor Indiana University student John D.Haseman in his stead.

In addition, two of Eigenmann's important works from his field research were published after his return from Guyana: "Cave Vertebrates of North America, a study of degenerative evolution" (1909) and "The fresh-water fishes of Patagonia and an examination of the Archiplata-Archelenis theory" in volume three of Reports of the Princeton University expeditions to Patagonian 1896–1899 (1909).

[12][22] Eigenmann made subsequent trips to South America that included Colombia (1912)(where he caught malaria)[21] and the high Andes in Peru, Bolivia, and Chile (1918–19).

[2][23] During World War I Eigenmann remained in the United States, where he spent his time writing up reports on his previous expeditions.

No longer able to conduct field research on his own, Eigenmann spent his later years assisting younger colleagues in mounting their own trips and sent some of his students, including Nathan Everett Pearson, on expeditions to the Atlantic slope of North America.

[2][23] Eigenmann also continued to write and present papers at academic conferences on various topics related to the fishes of North and South America.

In May 1926 Eignemann's declining health caused the family to leave Bloomington, Indiana, and return to San Diego, California, where he suffered a stroke in 1927.

[29][1][4] Carl Eigenmann is commemorated in the scientific names of a number of species, including: In 1970, a newly constructed residence hall building on the Indiana University's Bloomington campus, designed by Eggers & Higgins to be the tallest building in Monroe County, Indiana, was named after Carl H. Eigenmann.