Some Ecophysiological Responses of Male Tilapia (Oreochromis niloticus) to Thermal and Salinity Conditions

Abstract

The study was carried out on Nile tilapia fish (Oreochromis niloticus) at the Animal Physiology Unit, Animal production Department, Faculty of Agriculture, Cairo University during 1999 from May to November. The ultimate goal is evaluation of growth performance of this fish under major environmental conditions. The results are expected to be of basic practical value for application under Egyptian seasonal environmental conditions.

The experimental study either for fry or fingerlings incorporated six treatments (Tl-T6) between two temperature degrees (28.59, 33 °C for fry and 23.91, 33 °C for fingerlings) and three salinity levels (0.1, 15 and 30 ppt). The experimental assessments were carried out to: I)- Test changes in water vital concentrations of dissolved oxygen and pH values. 2)- Detem1ination of fry response particulary survivability and growth rate. 3)- Studies ofeco-physiological response of fingerlings to that studied environmental condition (thermal and salinity) and its reflection on the growth performance. The treatments of fry lasted for 30 days while that of fingerlings was extended for 42 days.