|Green, Bartholomew - Bart|
Submitted to: Journal of the World Aquaculture Society
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/20/2003
Publication Date: 3/20/2004
Citation: Green, B.W., Engle, C.R. 2004. Growth of stocker channel catfish to large market size in single-batch culture. Journal of the World Aquaculture Society. 35:25-32. Interpretive Summary: Catfish farmers increasingly are producing fish larger than the traditional size of 0.45-0.57 kg/fish in order to meet processing plant requirements for larger fish. Channel catfish production ponds rarely are harvested by draining, rather the market size fish are captured with a seine net and sent to the processing plant, and small fingerling catfish are stocked into the pond to replace the fish harvested. Research was needed because there is limited information on how fast catfish grow and convert feed to flesh beyond the 0.45-0.57 kg/fish-size. However, it is difficult to measure growth precisely when the population is composed of large and small fish. In this experiment, growth rate, production, and feed conversion efficiency were evaluated for 0.26-kg channel catfish stocked alone in 0.1-ha earthen ponds and grown to a harvest weight of 0.60, 0.72, 0.91, or 1.17 kg/fish. Channel catfish growth was linear for all groups of fish. There were no differences in growth rate of fish grown to 0.60, 0.72 or 0.91 kg/fish. Fish grown to 1.17 kg/fish grew faster, but the faster growth only became evident after 164 days of grow out. The net yield of catfish was 3,062, 4,468, 5,919, and 8,355 kg/ha for fish grown to 0.60, 0.72, 0.91, and 1.17 kg/fish, respectively. The feed conversion efficiency was similar for the four harvest weights. Thus, farmers can grow channel catfish rapidly up to an individual size of 1.17 kg/fish at a feed conversion that is as efficient as it is for growing a fish to a size of 0.60 kg/fish.
Technical Abstract: Catfish farmers increasingly are producing fish larger than the traditional size of 0.45-0.57 kg/fish in order to meet processing plant requirements for larger fish. Production of larger channel catfish (Ictalurus punctatus) in multiple-batch culture has been investigated in a few studies, but the impact of understocked fingerlings on growth of carry-over fish is unknown. Thus, growth of channel catfish to larger market sizes is best evaluated in single-batch culture. However, there is little data in the scientific literature on growth of channel catfish to sizes larger than 0.57 kg/fish in single-batch culture. The present study was conducted to quantify growth, feed conversion ratio, net daily yield, and net and total yield of stocker channel catfish grown in single-batch, one-season culture to mean individual weights of 0.60, 0.72, 0.91, or 1.17 kg/fish. Channel catfish (mean weight = 0.26 kg/fish) were stocked into 12 0.1-ha ponds at 11,115 fish/ha. Fish were fed a 32% crude protein floating extruded feed once daily to apparent satiation. When the average weight of the fish population reached the target weight, three randomly selected ponds were harvested. Fish growth was linear in all treatments. Growth rates were similar for fish grown to 0.60, 0.72, and 0.91 kg/fish, and significantly lower (P < 0.05) than for fish grown to 1.17 kg. Variation in individual fish weight increased linearly with increased duration of culture period. Feed conversion ratio averaged 1.9 and did not differ significantly among treatments. The percentage of the fish population at harvest that fell within the 0.57-2.04 kg-size range preferred by processing plants increased from 56.6-98.5% as the mean weight at harvest increased from 0.60 to 1.17 kg/fish.