Abstract
Single- and mixed-size cohorts of small (18 g) and intermediate (34 g and 60 g) fingerlings, and stocker (270-300 g) channel catfish, Ictalurus punctatus, were grown in ponds at 12,500/ha for two years. Year 1 compared single cohorts (18 g, 60 g, or stockers) to mixed-size culture of these cohorts. Year 2 compared a mixed-cohort treatment (18 g, 34 g, and carryover (CO) fish), and two, two-cohort treatments (18 g or 34 g and CO). Daily growth of 18-g fingerlings was less in triple-than single-cohort culture (0.98 g/day vs. 1.55 g/day) during Year 1. Sixty-gram fingerlings and stocker-size fish grew less (P <0.05) alone than in triple cohorts. Stockers also grew more (P <0.05) in double- than single-cohort culture. Nearly 29% of single cohort 18-g fingerlings reached marketable size (≥600 g); 14% in double cohorts, and none in triple cohort ponds. All pairwise comparisons of diet costs were significantly different during Year 1. All pairwise comparisons of yield from Year 1 were significantly different. Yield was similar among treatments during Year 2, and for the study totals. Return over fingerling and diet costs during Year 1 was greatest from single-cohort culture of stocker-size fish ($5885/ha). Return was similar among treatments during Year 2 ($6803-$7197/ha). All pairwise comparisons for the project totals were significantly (P <0.05) different. Multicohort culture produced better returns than single-cohort culture of 18-g ($1105/ha) or 60-g ($845/ha) fingerlings.