Technical Abstract: Studies were conducted in 15 1-acre and six ¼-acre ponds over several years to determine the effect of low dissolved oxygen (DO) concentration on food conversion ratio (FCR), food consumption, growth, and net production of blue catfish (BC), channel catfish (CC), and their hybrid (BC X CC). Control ponds in each study were maintained with a minimum DO concentration above 4.3 mg/L during the peak feeding months of the growing season (June-September); test ponds were maintained at 1.4 – 3.0 mg/L in different studies. The fish were stocked as fingerlings and fed once daily to apparent satiation and clean harvested at the end of the growing season in all studies. Results previously reported (Aquaculture 2009, P.257) demonstrate that food intake is reduced when DO drops below 3.0 mg/L, but low DO has less of an impact on feed consumption of BC than CC. At a mean minimum DO concentration of 1.7 mg/L, food consumption of CC was reduced by 45%; at 1.6-1.7 mg/L, feed consumption of BC was reduced by only 21%. Preliminary data indicates that BC X CC respond similarly to BC. FCR was poorer in larger ponds, but similar among species and was not affected by DO within the range of concentrations examined. We would expect a poorer FCR at lower DO concentrations (below 1.5 mg/L) as a greater proportion of the increasingly restricted feed goes toward maintenance. Catfish can be grown from egg to food fish in two seasons, but reduced growth resulting from restricted feeding may extend the production cycle by several years. Increased mortality during an extended production cycle may cause the poor FCR’s currently reported from the industry. Management should focus on reducing the length of the production cycle to improve FCR’s.