In the late 1940s Chaplin began his ichthyological work in Nassau, Bahamas, as a research associate for Philadelphia's Academy of Natural Sciences.
[1] Over the next 15 years, working with his Academy colleague Dr James Böhlke, he studied and collected over 500 species of Bahamian fishes, 65 of them never before described.
[2] Their work led to the co-authorship of Fishes of the Bahamas and Adjacent Tropical Waters (1968, with a new edition published in 1992).
[3] Chaplin and Bohlke pioneered the use of SCUBA gear and the organic ichthyocide rotenone in collecting specimens.
Chaplin was a recipient of the International Oceanographic Foundation's Angling Award for his contributions to marine science.