Author
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Freeman, Donald |
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Submitted to: Journal of Applied Aquaculture
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 1/30/1998 Publication Date: N/A Citation: N/A Interpretive Summary: Feeding fish tends to be an art rather than a science. In the case of catfish of all one size, called single-batch culture, scientists agree that feed particle size should start out small and gradually became larger as the fish grow. Essentially all feeding recommendations for catfish are based on just such a single-batch criteria. However, in practice, almost all catfish are grown under some form of multiple-batch culture where several size classes of fish are present in each pond. A study was conducted to evaluate the effects of initially feeding a small-diameter, fingerling feed on growth in single-size and mixed-size catfish ponds., Sixteen, 0.25-acre ponds were stocked at 6,000 fish/acre with eight ponds containing small fingerlings only and eight containing mixed-sized (85% fingerlings and 15% larger fish). Half the ponds representing each population group were fed initially for five weeks with a small diameter (1/8-inch) feed while the other half were fed a standard-size (1.4-inch) feed. After five weeks, ponds receiving the smaller feed were switched to the standard-size feed for the remainder of the 21-week study. Under mixed-size culture, there was no significant difference in final weight gain among either fish population due to initial feed size. Fingerlings produced under the single-batch scenario weighed 42% more at week 21 than fingerlings cultured with larger fish. There were no differences in total feed consumption between the mixed-size treatments. The practice of initially feeding a smaller-diameter ration to ponds containing mixed sizes of catfish appears to offer no advantage with respect to fingerling growth. Technical Abstract: A study was conducted to evaluate the effects of initially feeding a small- diameter, fingerling feed on growth in single-size and mixed-size catfish ponds. Sixteen, 0.1-ha earthen ponds were stocked at 14,820 fish/ha. Eight ponds were stocked with fingerling-only (19 g initial weight) populations and eight ponds with a mixed-size population of 85% fingerlings sand 15% third-year (307 g initial weight) fish. Half the ponds representing each population group were fed initially for five weeks with a small diameter (3.2 mm), fingerling feed while the other half were fed a standard-size (6.4 mm) feed. Each of the four feed/population combinations in the 2 x 2 factorial design was replicated in four ponds. Under mixed- size culture, there was no significant difference in final weight gain among either fish population due to initial feed size. Fingerlings produced under the single-batch scenario weighed 42% more at week 21 than fingerlings cultured with larger fish. There were no differences in total feed consumption between the mixed-size treatments. Competition between the two size groups coupled with a poorer feed conversion for larger catfish, or a combination of both, likely resulted in the feed consumption results. The practice of initially feeding a smaller-diameter ration to ponds understocked with moderately-sized fingerlings appears to offer no advantage with respect to fingerling growth, at least under the conditions of this study (e.g. satiation feeding). |
