Japanese eels(Anguilla japonica)are induced to maturation and spontaneous spawning,the hatched larvae are tried to rearing. Besides, the larvae are adapted to fit thefreshwater environment, maybe in this way, the survival rate and survival record of datecan be elevated.It is now known that thyroid hormones can be transferred into eggs and larvae, suggestthyroid hormones may play an important role during early larval development of fish.Attempts to the eel fry has extremely heavy mortalities occurring during the 2 or 3 dayfrom hatching and just can servival a few days . The aim of this study is to investigatethe effects of thyroxine on egg hatching and larval development in Japanese eel.Artifical reproduction of Japanese eels has been attempted for a long time.Severalresearch groups succeeded in inducing spawning of the eel by repeated gonadotropintreatment ,but can not obtain eel larvae successfully. The osmolarity changes of theJapanese eel in different life stage is to be investigated. To set the suitable environmental condition for artifical reproduction of the eels.The aim of this study is to investigate the suitable inclusion of fermented soy protein inthe diet for silver perch, Bidyanus bidyanus. The utilization of dietary crystalline aminoacids, especially methionine, by silver perch is also to be investigated in this study.Furthermore, the influence of dietary amino acid pattern on amino acid pool of fish willbe determined after the termination of growth trial.In intensive rearing system, increasing fish stocking density is one way to optimizeproductivity. However, high rearing density is also a potential source of stress that mayconstrain fish growing capacity. The influence of stocking density on the growth ofAmur river sturgeon Acipenser schrenckii will be investigated in this study. Differnentgrowth stage of juvenile sturgeon will be reared in concret ponds with three stockingdensity. According to the results of growth trials and changes of water quality, theoptimal stocking density for culturing Amur river sturgeon will be recommended.Zacco spp. is an endemic freshwater fish that widely distributs in the mountain streamsof Taiwan. Zacco are major fishing-sport fish in the river and it will develop a endemicornamental fish. Fang et al.(1993) reported that there was a marked difference inbreeding season between Zacco fish in Taiwan and Japan. In this study, the inducementof oocyte maturation and ovulation with different hormones and doses, natural matingbehavior and recuitment of juvenile fish will be investigated.