Algae Cultivation for Fish Feeds using Nutrients from Closed Recirculating Aquaculture System

摘要

Recently, closed recirculating aquaculture system which is one of the methods for fish farming has attracted attentions. The system enables seafood to be efficiently and safely cultured by the circulation of limited water. However, this system is difficult to be prevailed because it has high initial cost and maintenance cost. In this study, Chlorella sp. as feeds for larval fish were cultured using nutrients from water in the aquaculture system. Water samples were collected 4 points including breeding tank, sedimentation tank, regulating tank, and biological filtration tank. Optimum dilution ratio of water samples for algae cultivation and cost analyses of the cultivation system were investigated. As a result, it was revealed that algae cultivation with 4 times diluted sample from the regulating tank was the most suitable. The concentration of the cultivated algae was 50.8±7.6 mg/L, and cost for algae cultivation as feeds for larval fish 5,960 yen. It was higher than that for feed on the market(31.8 mg/L), and cost for algae cultivation was cheaper than that for purchase feed on the market(18576 yen). Therefore, it was suggested that usage of the cultivated algae as fishery feeds was effective.