Article ID Journal Published Year Pages File Type
2843745 Journal of Thermal Biology 2008 8 Pages PDF
Abstract

Growth of juvenile Nile tilapia, Oreochromis niloticus (Maryut strain) was studied under laboratory conditions. Four thermal regimes (22, 26, 30, and 34 °C) were tested on 480 20-day-old fry.Significant (P<0.05) effects of temperature on growth were observed. Results showed that the final mean weight was significantly higher at 26 and 30 °C than at 22 and 34 °C. Feed conversion ratio (FCR) and daily weight gain (DWG) were better at 26 and 30 °C. At all temperatures, survival rates were not affected. These results suggest that the best growth and feed utilization of O. niloticus juveniles may be higher at 26 and 30 °C.A second experiment was performed to assess the effect of ambient water temperature during the period of sex differentiation on the sex ratio. Results showed that the high-temperature (almost 36.90 °C) treatments yielded a significantly higher proportion of males (64.20–80%) with lower survival rates (60–81%), whereas the sex ratio of progenies reared at temperature below 36 °C never deviated significantly from the balanced sex ratio.This study provided clear evidence that the exposure of progenies to “masculinizing” temperature may significantly decrease the survival rate of fish.

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