1. USDA, Agricultural Research Service, Harry K. Dupree Stuttgart National Aquaculture Research Center, 2955 Highway 130 East, Stuttgart, AR 72160, USA
2. USDA, Agricultural Research Service, Aquatic Animal Health Research Unit, 990 Wire Road, Auburn, AL 36832, USA
3. School of Fisheries, Aquaculture and Aquatic Sciences, Auburn University, Auburn, AL 36849, USA