Growth of living organisms is a fundamental biological process. It depicts the physiological development
of the species related to the environment. Mathematical development of growth curve models has a long
history since its birth. We propose a mathematical model to describe the evolution of relative growth rate
as a function of time based on a real life experiment on a major Indian Carp Cirrhinus mrigala. We establish
that the proposed model is able to describe the fish growth dynamics more accurately for our experimental
data than some existing models e.g. logistic, Gompertz, exponential. Approximate expressions of
the points of inflection and the time of achieving the maximum relative growth rate are derived. We
study, in detail, the existence of a nonlinear least squares estimator of the model parameters and their
consistency properties. Test-statistics is developed to study the equality of points of inflection and equality
of the amount of time necessary to achieve the maximum relative growth rate for a species at two
different locations. Using the theory of variance stabilizing transformations, we propose a new test statistic
to test the effect of the decay parameter for the proposed growth law. The testing procedure is
found to be more sensitive in comparison with the test based on nonlinear least squares estimates.
Our proposed model provides a general framework to model growth in other disciplines as well.