Interactive effect of Water temperature and nitrate fertilizers on growth, survival, and hatching success of eggs, embryos and larvae of African Catfish (Clarias gariepinus, Burchell 1822)

The study assessed the interactive effect of water temperature and nitrate fertilizers on growth, survival, and hatching success of eggs, embryos and larvae of African catfish Clarias gariepinus. 100 fertilized eggs of C. gariepinus were incubated in glass flasks (1000 ml) each filled to 800 ml mark with groundwater containing (0, 5, 10, 15 and 20 mgL-1 of NO3 -N) nitrate levels. Flasks were randomly placed in water bath set at (25°C, 28°C, and 31°C) temperature levels in triplicates. 30 larvae were maintained in the same hatching solution and temperature. Data were collected from egg to ten days post-hatching in November 2017. The results showed that the tolerable limit of C. gariepinus eggs, embryos and larvae to nitrate fertilizers was 10 mgL-1 of NO3 -N at 28°C and 31°C and range between 5 and 15 mgL-1 of NO3 -N at 25°C. We concluded that eggs, embryos and larvae of C. gariepinus can withstand a maximum of 10 mgL-1 of NO3 -N at temperatures ranging from 25°C to 31°C. It is therefore recommended that excess application of nitrate fertilizers in Agricultural fields should be discouraged in order to protect C. gariepinus hatchlings from nitrate toxicity