Reporting Fish Growth: A Review of the Basics

Aquaculturists typically report growth using absolute (g/d), relative (% increase in body weight), and specific growth rates (%d). Less frequently, von Bertalanffy Growth Functions (VBGF) are used. Each of these rates is a numerical representation of growth which assumes a specific relationship between size and time (linear, exponential, or asymptotic). Aquaculturists typically determine size at time throughout their experiments. Unfortunately, the intermediate data points are usually ignored when computing growth rates (except for VBGF) and the appropriateness of the method for calculating growth for a particular data set is not tested. This paper reviews the basis and computation of each of the growth rates in an effort to encourage aquaculturists to use the appropriate growth rates.