There’s a big catch with Asian carp. They weigh in at 150 pounds and have an appetite for more than plankton. Escaping from catfish farms, where they were introduced to clean up algae, the Asian carp has been devastating the ecosystems of Midwestern rivers for 40 years. By out-breeding and out-eating native species, the fish now makes up 80 percent of the biomass in some U.S. rivers. If native fish are ever to seize the day, these invaders will have to go.