In this study, the effect of the pituitary glands on the development of Japanese eels ( Anguilla japonica ) is investigated by two factors, seawater temperature and different sources of pituitary gland. The pituitary glands were collected from dolphin fish,Coryphaena hippurus . Our experiments were conducted in cold seawater (21-23℃) and warm seawater (28-30 ℃) when dolphin fish pituitary gland,Clarias fuscus pituitary glands and saline were injected. The results show that the pectoral fins of the eels began to darken with the injection of Coryphaena hippurus pituitary glands and Clarias fuscus pituitary glands. The Japanese eel with gray pectoral fins were injected with saline. After injecting for 16 times, the results show that the optimum gonadosomatic index (GSI) of eel was 10.42 ± 10.25%, which was cultivated in warm seawater and injected with Clarias fuscus pituitary glands; the lowest index was in cold seawater, with the injection of saline (GSI value of 0.70 ± 0.00%). The results of histological observations of the oocyte of Japanese eels, show that the egg cells become larger at vitellogenesis stage with the injection of dolphin fish pituitary gland and Clarias fuscus pituitary glands, while the oocytes were only in primary oocyte stage with the injection of saline.