Effect of Water Temperature on the Egg Production and Egg Viability of the Monogenean Heterobothrium okamotoi Infecting Tiger Puffer Takifugu rubripes

Abstract

Tiger puffer experimentally infected with Heterobothrium okamotoi was given gradual changes of water temperature, and the effect of temperature on the production and viability of the parasite eggs was examined. Among 10, 15, 20, 25 and 30°C, the highest egg production rate was observed at 25°C. While most of eggs produced at 10 or 20°C hatched at 20°C- incubation, those produced at 30°C decreased in hatching rate at 20°C- or 30°C- incubation. Eggs produced at 26°C or more contained morphologically abnormal ones. These results indicate that the optimal temperature for the egg production of H. okamotoi is approximately 25°C.