Duration of feeding and indirect selection for growth of tilapia

Abstract

Duration of spontaneous feeding was observed at three times each day in a laboratory population of nine juvenile tilapia (Oreochromis mossambicus). Growth of the fish was measured as change in length and weight, and also as uptake of ¹⁴C-labelled glycine by isolated scales. Duration of the first morning feeding was highly correlated with all measures of growth and was independent of initial size. Later feedings were not correlated with growth. Selection on feeding duration could be used to select indirectly for growth rate; this might be a valuable procedure where individuals in the population are not exactly the same age (i.e., where size-at-age is an inaccurate measure of growth).