Opponents of Michigan fish farms say there is no room for them in the lakes because of sport fishing and other recreational activities. sfgamchick/Flickr hide caption

itoggle caption sfgamchick/Flickr

Carp are collected at a breeding farm near the Belarus village of Ozerny in November 2013. Researchers say there's a lot the aquaculture industry can do to be more efficient. Viktor Drachev/AFP/Getty Images hide caption

itoggle caption Viktor Drachev/AFP/Getty Images

Employees at Pan Fish USA, a salmon fish farm, unload fish feed on Bainbridge Island, Wash. Ron Wurzer/Getty Images hide caption

itoggle caption Ron Wurzer/Getty Images

Thierry Chopin from the University of New Brunswick examines a raft that holds strings of seaweed. The seaweed grows around pens of farmed salmon and soaks up some of the nutrients that would otherwise pollute the Bay of Fundy. Richard Harris/NPR hide caption

itoggle caption Richard Harris/NPR

Catfish swim in a tub outside the Osage Catfisheries office. Kristofor Husted/KBIA News hide caption

itoggle caption Kristofor Husted/KBIA News

The fly larvae in the AgriProtein factory feed on cow blood and bran. Courtesy of Jason Drew hide caption

itoggle caption Courtesy of Jason Drew