Fish were fed to apparent satiation twice daily during the week, and once daily on weekends, which was approximately 4–7% of body weight. Fish from each aquarium were counted and weighed collectively at 2-week intervals to monitor growth and adjust feed rations. At the end of the trial all fish were counted and weighed in groups. Eighteen individual fish per aquarium were euthanized with an overdose of MS-222 (200 mg/L water), homogenized into one pooled sample, and lyophilized for subsequent ash and mineral analysis as described for the diets. Remaining live fish in each aquarium were maintained on their respective diets for 1 day prior to collection for GI microflora analysis.