Interaction of growth with social behaviour in Tilapia zilli raised in three different temperatures

Three thermal levels were tested on 10-day old T. zilli fry obtained from one spawning to study the effects of temperature on the occurrence of growth depensation in the population reared under controlled environmental conditions. Results showed highest individual growth rate, mortality rates and growth depensation at 30 °C whilst the greatest biomass increase was obtained at an intermediate temperature (27 °C). The enhanced depensation and high mortality rates at the upper limit of the thermal gradient for growth of T. zilli were attributed to an alteration in the behaviour of fish which favoured a few, large, dominant and socially aggressive individuals.