World Aquacluture Magazine - September 2020

WWW.WA S.ORG • WORLD AQUACULTURE • SEP TEMBER 2020 13 I n each issue of World Aquaculture , we highlight a new and exciting research paper from the Journal of theWorld Aquaculture Society. This issue’s selected research publication recently appeared in volume 51(4):931-943 and is titled “Effects of long-term restricted feeding followed by full feeding on growth, processing yield, fillet proximate composition, and economics of market-size hybrid catfish, ♀ I ctalurus punctatus × ♂ Ictalurus furcatus .” The authors are Menghe H. Li, David J. Wise, Ganesh Kumar, Brian G. Bosworth, Charles C. Mischke, Suja Aarattuthodiyil, WilliamRutland and Penelope M. Lucas of the National Warmwater Aquaculture Center in Stoneville, MS. There is a cyclical nature to the supply of catfish in food markets in the USA that leads to serious gluts in supply of market-size fish every few years. This problem is exacerbated in hybrid catfish ♀ I ctalurus punctatus × ♂ Ictalurus furcatus as they feed more and growmore rapidly than either parent species. Catfish producers are faced with the choice of holding harvest- ready fish on restricted feeding regimes or ceasing feeding altogether. Recent Research Highlight from the Journal of the World Aquaculture Society The chosen feeding regimes can lead to significant weight loss and yield loss by carcass weight. Alternatively, they can generate high feed costs and potentially animals growing too large to be successfully marketed. Feeding regimes to minimize economic impacts for these holding periods are essential. In the August 2020 issue of JWAS, Menghe Li and co- authors examined pond-grown market-size catfish fed to apparent satiation either once or twice weekly over four months. These “restriction” treatments were followed by a subsequent normal or full-feeding period of either 15 or 30 days. Feeding fish once weekly led to a weight increase of 30 percent, while twice weekly led to a 70 percent weight increase. Fifteen days of full feeding after 30 percent restriction were not sufficient to fully return fillet yield (carcass yield) to normal levels. Overall, the economic recommendations of the study are that fish fed twice weekly during restricted feeding can be directly harvested when required. Fish fed once a week require 15 days feeding at full rates to improve fillet yield. —Matthew Slater, Executive Editor, JWAS