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Abstract
Abstract
The objective of this study was to determine the effect of different sub-lethal concentrations of UIA-N (0.01, 0.05, 0.1, 0.15) and control (0.004 mg/l), different levels of pH (6, 7, 8 and 9) and also different degrees of temperature (15, 20, 30) and control (25°C) on growth performance, survival rate and some physiological parameters on Nile tilapia (O. niloticus) fingerlings. Average body weight of Nile tilapia were 19.0± 1.0 g reared in glass aquaria (40×70×60 cm). The fish fed on diet contained 26.58% protein. The physico-chemical analysis of water and histopathological changes in kidney, liver and gills of the fish were recorded in the first experiment. Some blood parameters were recorded at the beginning and at the end of each experiment . In addition , growth measurements were recorded every 15 days interval during each experiment. The water changed twice daily at 100% of water size. Also LC50 was determined.
The results of the study showed that Nile tilapia (O. niloticus) fingerlings with average body weight (19.0± 1.0g) were more suitable to be cultured at water temperature (25-30)°C, pH (7-8) and UIA-N of (0.01-0.004) mg/l for optimum growth performance and survival rate than other water criteria. Therefore, it can be recommended to be carried out under similar experimental conditions.
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Key words: Nile tilapia (O. niloticus), unionized ammonia, temperature, pH, histopathology, hematology, growth, survival rate, LC50.