A comparative study on production efficiency of 4 selected feed mixes differing in their nutrient levels, used in intensive culture of European wels (Silurus glanis L.) was conducted in 2001. Experiments were carried out in an active European wels culture facility equipped with a flow through system with heated water (Tisova Farm, České rybářství Mariánské Lázně, Ltd., Czech Republic). The initial individual fish weight was 450 g; water temperature during the 112 days of the experiment averaged 23ºC. The fish were kept, at 60 kg/basin stocking density, in 8 about 3 m3 basins; the water flow rate was 1-3 l·s^-1. The feed mixes used were Aqualife 14 (44% protein; 14% fat), Aqualife (42% protein, 22% fat), T 70 (44% protein, 27% fat), and Dan-EX 1344 (44% protein, 13% fat). The major parameters monitored were: fish mortality, growth, SGR, and FCR. Additionally, nutrient retention, external parameters, fish tissue chemical composition, as well as selected haematological and biochemical blood plasma were recorded. The following results were obtained: the Aqualife 14- fed fish attained 1 170 g individual weight, 0.85%·d^-1 SGR, and 1.43 FCR; the fish fed Aqualife 17 attained 1366 g individual weight, 0.95%·d^-1 SGR, and 1.26 FCR; when fed T 70, the fish grew to 1 377 g individual weight and attained SGR of 0.99%·d^-1 and FCR of 1.27; the DanEX-fed fish attained 1 110 g individual weight, 0.81%·d^-1 SGR, and 1.52 FCR. The best cost-benefit result was achieved by using Aqualife 17. Other parameters monitored showed a significant (p < 0.05 and p < 0.01) effect of the feeds applied.

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