Effect of Feeding Frequency on Feed Consumption, Growth, and Feed Efficiency in Aquarium-reared Norris and NWAC103 Channel Catfish (Ictalurus punctatus)*

—A 6-wk feeding study was conducted to determine the effect of feeding frequency on growth rate of juvenile Norris and NWAC103 channel catfish, Ictalurus punctatus, reared under laboratory conditions. Four replicate groups of Norris and NWAC103 catfish (average weight of 4.0 6 0.2 g/fish, SEM) were fed to visual satiety at different feeding frequencies (one, two, or three times daily). The percent of total daily food consumed for Norris catfish fed three times daily (0800, 1200, and 1600 h) was 44.4, 27.7, and 27.9%, respectively, while NWAC103 catfish consumed 42.9, 26.7, and 30.4%, respectively. Specific growth rate and feed intake were higher in fish fed three times daily compared to fish fed once and twice daily for both strains. Feed efficiency was reduced in NWAC103 fed three times daily compared to fish fed once or twice, while feed efficiency was similar among the Norris treatments. Gastrointestinal (GI) tract index ([weight of GI tract/weight of fish] 3 100) decreased in NWAC103 catfish as feeding frequency increased, while a similar nonsignificant trend was also observed in Norris catfish. The results of this study demonstrate that aquarium-reared Norris and NWAC103 catfish fed three times a day consume more feed and gain more weight than catfish fed once or twice a day. The observed decrease in the GI index as a result of feeding more frequently demonstrates that the size of the GI tract increases, relative to body weight, when catfish are fed only once a day. Under laboratory conditions, the number of times a day the fish are fed should be considered when trying to maximize growth of NWAC103 and Norris strains of catfish. Fish growth is influenced by feed availability and intake, genetics, fish age and size, environment, and nutrition. Of these factors, feed intake is perhaps the principal factor affecting growth rate of fish (Li et al. 2004). Many studies have compared growth rates of the NWAC103 to different strains of channel catfish, Ictalurus punctatus, such as Mississippi ‘‘normal’’ and Norris catfish and have found that the NWAC103 channel catfish exhibits superior growth characteristics (Silverstein et al. 1999; Wolters et al. 2000; Li et al. 2001; Jackson et al. 2003; Bosworth et al. 2004). In general, studies find that the NWAC103 consumes more feed and grows faster. It has been suggested that the faster growth of the NWAC103 strain of channel catfish is as a result of their ability to consume more feed (Li et al. 2001). Furthermore, there may be a genetic component to their ability to consume more feed (Silverstein et al. 2001). Laboratory studies with channel catfish have shown that feeding frequency affects growth performance of these fish. Andrews and Page (1975) fed catfish (mean initial weight of 53 g/fish) 1, 2, 4, and 8 times daily, and even 24 times daily to apparent satiation. Their results showed that weight gain was substantially reduced in fish fed once daily compared to feeding two or more times daily. In addition, feed conversion was not affected by frequency of feeding. The results of that study suggested that feeding two times daily to satiation was sufficient for maximal growth. However, their study did not examine feeding three times daily (Andrews and Page 1975). In addition, the strain of catfish used in the study was not described. Increasing catfish growth is a primary goal of our broodstock management program at the NationalWarmwater Aquaculture Center (NWAC) 1 Corresponding author. * Mention of trade names or commercial products is solely for the purpose of providing specific information and does not imply recommendation or endorsement by the US Department of Agriculture. JOURNAL OF THE WORLD AQUACULTURE SOCIETY Vol. 37, No. 4