Fishmeal replacement with a mixture of plant protein (PP) raw materials (soya, wheat gluten meal, corn gluten meal and rapeseed meal) in diets for 300-950 g turbot was tested. Eight different diets with fishmeal protein stepwise varying from 53.7% of crude protein (CP) to 93% of CP of the total protein in the diet were tested. The fish was weighed at monthly intervals for following of weight development and calculation of specific growth rates, daily feed intake and feed conversion ratio. At the end of the experiment, fish was sampled for sensory evaluation. Average final weight was 950 g and did not vary between the experimental groups. There were no effects of dietary treatment on specific growth rates, daily feed intake, feed conversion ratio or sensory attributes measured. The least-cost diet (with 53.7% fishmeal protein) is about 12% lower in raw material cost (based on material price of diet components) than the all fishmeal diet. The results therefore indicate that the raw material cost in feed for ongrowing turbot can be reduced considerably without any negative effect on growth and feed utilization. K E Y W O R D Sdiets, growth, protein source replacements, sensory evaluation

A dietary study was conducted to investigate the effect of partly substituted levels of fish meal in feed for juvenile (140-500 g) turbot (Scophthalmus maximus Rafinesque) on growth performance. The experimental diets were formulated to contain 53, 73 and 93 % fish meal protein and different levels of plant protein substitutes (wheat meal, corn gluten meal, soybean meal and canola meal) with three replicates for each diet. Fish fed 53% fish meal diets had lower final mean weights compared to fish fed the 93% fish meal diet, whereas the 73% fish meal group displayed intermediate values. However, only minor differences were found in specific growth rate, feed conversion ratio, daily feed intake and total feed consumption between dietary treatment groups. Overall the findings demonstrate that substitution of fish meal by plant protein raw materials down to 53 % fish meal protein (44% replacement) does not affect overall specific growth rate, feed conversion ratio or feed intake in juvenile turbot (<500 g).