Percy Viosca Jr. was a freshwater and marine biologist who specialized in the fauna of Louisiana and in the aquaculture of sportfish.
His early career included many scientific publications with taxonomic contributions and life histories of the animals he studied.
His reports on this subject often take examples from his work as a fisheries consultant and the biological supply company he operated.
His work also included mosquito control, riparian and marshland studies, flood control, taxonomic work with native Louisiana irises, newts, and snakes, culture of crawfish and environmental impact of oil refinery practices.
He maintained that man made flood protection, deforestation, deepening channels, and the cutting of navigation and drainage canals across the southern Louisiana marshes, as a cause for erosion.