"We don't use pesticides or fertilizers," Pillow says. "The only chemical that we use is copper sulfate, if the fish get a fungus." And copper sulfate is a relatively benign chemical that doesn't accumulate in the catfish and is only hazardous to people in doses higher than catfish can tolerate.
Pillow's operation is not uncommon among U.S. catfish farms, often considered the most eco-friendly operations in an aquaculture industry that's riddled with the same problems as land-based agriculture: dangerous synthetic pesticides, including formaldehyde-based Formalin and permethrin, which harms aquatic organisms other than fish; synthetic nitrogen- and phosphate-heavy fertilizers, which feed algae blooms; herbicides, such as the suspected hormone disruptor 2,4-D; antibiotics and growth hormones.
But even catfish farms with all their eco attributes are imperfect, says David Guggenheim, Ph.D., president of the non-profit 1planet1ocean. "In open systems, you can have a storm event and suddenly you have nitrogen flooding into surrounding fields, escapement of the fish and possible disease, and they're susceptible to air pollution and rainfall [which causes flooding]," he says. Escaped non-native fish, which contributed to farmed salmon's bad name, are problematic even in land-based ponds. Bighead carp, which are similar to catfish, were imported from Asia in the seventies to help remove algae from catfish ponds and are raised for supplemental income alongside the more desirable domestic channel catfish. In the wild, bighead carp compete with other native species for food. Also, like other aquaculture systems, catfish ponds are fed by a percentage of wild-caught fishmeal, albeit a much smaller amount than feed consumed by salmon.
Nevertheless, land-based aquaculture must grow if seafood suppliers want to meet the public's growing demand, says Guggenheim, a demand that cannot be met by current wild-fishing practices.
Source: The Green Guide