The effects of Geno hot spring cyanobacteria on growth, survival and morphology of gill tissue in killifish Aphanius dispar in normal and long term thermal stress environments

A killifish species Aphanius ginaonis occurs in Geno hot spring is one of the unique fish species that could successfully survive and acclimated to the high temperature of hot springs. In this study, we investigated the effects of Geno's cyanobacteria extracts on growth, survival and morphology of gill tissue in Aphanius dispar exposed to normal temperature and long-term thermal stress. For this purpose, 228 fish divided in four treatments including control (25°C), thermal (40-37°C), cyanobacteria control and cyanobacteria thermal. Our results showed significant affects of prolonged thermal stress in all growth parameters of A. dispar. At the end of the experiment at day 44, most of the growth parameters significantly decreased compared to the control group. The results showed that growth factors, including specific growth rate (SGR), weight gain (WG) and food conversion rate (FCR) in the control and the control – cyanobacteria groups were significantly higher than those of thermal and thermal- cyanobacteria treatments (p