Influences on feeding activity of channel catfish and sunshine bass fed to satiation in earthen ponds in Mississippi

Channel catfish Ictalurus punctatus and sunshine bass Morone saxatiliseX × Morone chrysopsX fed once daily to apparent satiation demonstrate wide day-to-day variation of feed consumed. Causes of daily variation in feed consumption are understood poorly, but it may be that meteorological and/or water quality conditions influence fish behavior or physiology in some way that affects appetite. Identification of conditions related to poor feed consumption may suggest managerial practices for increasing overall feed consumption, growth, and profitability of aquacultural enterprises. To examine factors that may affect feeding activity of channel catfish and sunshine bass, and to identify interrelationships among these factors, data on daily feed consumption and selected meteorological and water quality variables were compiled from eight channel catfish ponds and nine sunshine bass ponds between April to November in Mississippi. Factor analyses and regression analyses of the data indicated seasonal differences in the interrelationships among daily fluctuations in feeding activity and meteorological and water quality variables. Seasonal changes in feeding activity of channel catfish and sunshine bass was influenced most strongly by water temperature. Feeding activity increased in a curvilinearly with water temperature up to approximately 30°C for channel catfish, and approximately 31°C for sunshine bass. Above these temperatures, feeding activity decreased. Daily variation in temperature, as compared to seasonal variation, was smaller and had little influence on feeding activity. Meteorological conditions had an indirect effect on feeding activity because water temperature was influenced strongly by air temperature and other factors, but had limited direct effects on feeding activity. Water quality had no consistent influence on feeding activity, and was related to short-duration, pond-specific events in which atypically stressful conditions were experienced by the fish. Feeding activity of fish in this study did not appear to be related inversely to amount fed on previous days. Other than ensuring an adequate pond for survival and growth of fish, little managerial control of feeding activity seems possible. Practical control of the primary influence that water temperature and meteorological conditions have on feeding activity of channel catfish and sunshine bass, under typical pond culture conditions, would be difficult and cost-prohibitive.