Catfish is the major fish farmed in the United States, primarily in Mississippi, Louisiana, Texas and Alabama. Most catfish sold commercially are now farmed. Typically ponds used for raising catfish are constructed in relatively clean environments. The process involves digging a pit and using the top soil to create surrounding levees. Generally ponds are three to six feet deep and range in size from 10 to 20 acres. In the Mississippi Delta, the ponds are usually filled with pesticide-free groundwater. Outside the Delta, rainfall may be used as the water source to fill the ponds.

Catfish diets are mainly or entirely grain, which minimizes toxic contamination. In a recent study of farmed fish, about 45 percent of catfish samples had undetectable pesticide and PCBs contamination. When fish did contain pesticide residues, most were well below the level considered harmful to health. Apparently the toxic contamination in farmed catfish is usually much less than that found in wild catfish. To better ensure consumer safety, however, Santerre and co-workers suggested that the aquaculture industry should routinely test for pesticide residues in their products.

Average mercury level was under 0.01 ppm, which is low compared to the amount found in most fish and lower than the average for wild catfish. Barium, cadmium, silver, lead, and arsenic were detected only in a small percentage of catfish; and, when present, their levels were relatively low and deemed not to be a health hazard.