Acute hyperthermia and hypoxia tolerance of two improved strains of nile tilapia (Oreochromis niloticus)

Abstract Tilapia production in Ghana has been hit with episodes of stress and pathogen-induced mass fish kills which have anecdotally linked to the culture illegally imported Genetically Improved Farmed (GIFT) strains Nile tilapia, Oreochromis niloticus . This study was thus set up comprehensively assess tolerance GIFT strain a native tilapia (the Akosombo strain) following exposures hyperthermic hypoxic stressors. In series experiments, oxygen consumption ( M O 2 ), aquatic surface respiration (ASR), thermal limits hypoxia were assessed. The effects these stressors on haematological parameters also less tolerant performed ASR at higher levels than strain. Under progressive hypoxia, exhibited gill ventilations frequencies f V) trial indicated that O. thermotolerance this reflective LT 50 (45.1℃) max (48℃), compared 41.5℃ 46℃ respectively. These results imply it is crucial consider how performs under various environmental conditions changes during culture. Particularly, raising earthen ponds rich phytoplankton subject protracted extreme may detrimental physiological impact its growth welfare.