Abstract
The relationship between growth rate and fish size is described by the equation logeGw=a—0·4 loge W, where Gw is the specific growth rate and W is fish weight. Since the intercept (a) represents the loge Gw of a fish unit size, the relationship presents a method allowing comparison of data from experiments involving fish of different sizes. The application of the method is demonstrated by examining the effects of environmental temperature on growth rates of cod, Gadus morhua, and it is suggested that the optimum temperature for growth of cod is 13–15° C.