The effect of feeding regimen on growth, food conversion ratio and size variation in juvenile dusky kob <i>Argyrosomus japonicus</i> (Teleostei: Sciaenidae)

Abstract

Temperature, feeding frequency and feeding intensity are important determinants of fish growth in aquaculture. As part of a research and development programme to optimise husbandry techniques for a new mariculture species, the dusky kob, Argyrosomus japonicus, this study tested the effect of four feeding strategies on growth, food conversion ratio (FCR), condition factor, and size frequency distribution in this commercially important species. Treatments included a restricted ration distributed over three daily feedings, and feeding to apparent satiation either once, twice or three times per day, respectively. Fish fed to satiation once daily grew slowest at a daily feed intake similar to that of the restricted ration treatment. Fish fed the restricted ration of 3.4% body mass day^–1 (BM d^–1) had the best FCR-values. FCR was reduced at feeding intensities above 3.85% BM d^–1. Thus, growth of juvenile A. japonicus was a function of both daily food intake and food deprivation time. While feeding strategy did not influence size variability expressed as coefficient of variation for length and weight, size frequency distributions tended to become more left-skewed as feeding frequency increased. Juvenile A. japonicus within the size range of 7.5–35.0 g fish^–1 should be fed more than once daily at a feeding intensity of no more than 3.85% BM d^–1.

Keywords: FCR, growth rate, mariculture, ration size

African Journal of Aquatic Science 2011, 36(1): 83–88