Rainbow trout were reared in a stainless steel aquarium from Nov. 11, 1977 to June 12, 1978, and the following results were obtained : 1. The volume of water was about $400iota$ in a aquarium measuring $1m;(Length) imes1m;(Width) imes67cm(Height)$ and water depth 40 cm. Water was supplied for about 16 hours daily at a rate $3iota/min$ and was drained through the conical settling part in the middle of the aquarium bottom. Filter tank was about $23cm(W) imes23cm(L) imes40cm(D)$ and contained pebbles 30 cm in depth. Water recirculation rate was at)out $1,030iota/hr$, or 2.6 turn-over per hour. 2. During the first period (77 days), the trout grew from 88.3g to 229g in average, the total weight attaining 30.7kg. The food coefficient was 1.249, average daily increment 243.3g, average daily growth rate 1.245%, and the mortality was 2 smallest fish weighing 53 g, owing to unknown reason. During the second period (135 days), the trout grew from 239g to 555g in average, the total weight attaining 57.2 kg. The food coefficient was 1.447, average daily increment 279.8g, average daily growth rate $0.65\%$ and the mortality was 31 fish weighing 11,255 g, owing partly to miss-handling and partly to disease. 3. The feed consisting of fully domestic materials was prepared in this laboratory, and the feed conversion was not inferior to high protein commercial feed available in foreign countries. 4. The result of whole period for 212 days was 56.5 kg in gross increment, and based on this result, when $1iota/min$ full day inflowing water available, the net production will become 28.25 kg. So, if a 5000kg production is planned, $180iota/min$ or about $10.8m^3/hr$ be reauired, and the production in value frill become 15million won at local price at the expense of about 5.3 million won. From the result of this experiment, rainbow trout is feasible for commercial production in Korea with relatively small amount of well water and simplified water recirculation system.