Growth and Feed Efficiency of Juvenile Channel Catfish Reared at Different Water Temperatures and Fed Diets Containing Various Levels of Fish Meal

—Channel catfish Ictalurus punctatus do not feed well at low temperatures. It is generally thought that a diet containing fish meal enhances feed palatability at low temperatures since fish meal is highly palatable to fish. There is a lack of information on the effects of fish meal levels on the growth performance of channel catfish reared at low temperatures. Therefore, a study was conducted in a recirculating system to examine the effects of fish meal levels on the feed consumption, weight gain, and feed efficiency of juvenile channel catfish reared at various temperatures. Fish with an initial weight of 9.6 6 0.1 g were stocked in 23-L clear polycarbonate tanks maintained at approximately 17, 21, or 27 8C. The fish were fed with diets containing 0, 4, or 8% menhaden Brevoortia spp. fish meal for 9 weeks. There was a significant interaction between water temperature and fish meal level with respect to weight gain. At 278C, fish fed diets containing 4% and 8% fish meal gained significantly more weight than fish fed the all-plantprotein diet. However, the level of fish meal had no significant effect on the weight gain of fish at 178C or 218C. This suggests that the olfactory and gustatory responses of channel catfish to fish meal (up to 8% in the diet) may not be as sensitive at low temperatures as at optimum temperatures. The results also indicate that more than 4% fish meal in the diet is not beneficial for the optimum growth and feed efficiency of channel catfish fingerlings raised at 278C. Unlike warm-blooded animals, channel catfish Ictalurus punctatus do not feed consistently when water temperatures are below 208C and generally stop eating at temperatures of 108C (Robinson et al. 2004). Many catfish producers choose not to feed during winter months for various reasons, one of which is that it is difficult to see a positive response from a winter feeding program. However, based on research results, winter feeding is beneficial, though the magnitude of benefit from a winter feeding program depends on the severity of winter. Fish will gain (if fed) or lose (if not fed) more weight during a mild winter than during a cold one. A recent study conducted at Delta Western Research Center, Indianola, Mississippi (E. H. Robinson, unpublished data), as well as research by Lovell (1989), has shown that food-sized channel catfish gain 15–18% of their body weight during a mild winter (average daytime water temperatures from November 15 to March 15 were about 11–138C). Fingerlings were shown to gain up to 45% (Lovell 1989) if they were fed during the winter. Because the feeding activity of channel catfish is reduced at low temperatures, it is hypothesized that adding a highly palatable feedstuff, such as fish meal, to the diet would increase feed consumption by catfish at low temperatures. There have been anecdotal reports that channel catfish eat more feed at low temperature when they were fed diets containing fish meal; however, this has not been scientifically validated. There are several reports on the effects of dietary fish meal levels on growth and feed efficiency of channel catfish fingerlings and food fish raised during the growing season or at optimum water temperatures, but results are inconsistent. Some studies show that complete removal of fish meal in the diet reduces fish growth (Andrews and Page 1974; Mohsen and Lovell 1990; Robinson and Li 1998; Li et al. 2006). In contrast, other reports indicate that nutritionally balanced all-plant diets can provide similar growth and feed efficiency as diets containing fish meal (Webster et al. 1992; Robinson and Li 1994; Reigh 1999; Li et al. 2003). The objective of the present study was to evaluate effects of dietary fish meal level on feed consumption, weight gain, and feed efficiency of channel catfish at various water temperatures. * Corresponding author: [email protected] Received August 23, 2007; accepted October 16, 2007 Published online June 2, 2008 347 North American Journal of Aquaculture 70:347–352, 2008 Copyright by the American Fisheries Society 2008 DOI: 10.1577/A07-078.1 [Article]