Diets containing three levels of fish meal (4, 6 and 8 %), each supplemented with synthetic lysine at four lysine levels (0,7; 0,8; 0,9 and 1,0 %) were formulated to contain 12,65MJ of ME per kilogram air-dry feed and individually fed ad lib. to 48 Landrace x Large White pigs (24 boars and 24 gilts) for the live mass interval 20 to 60 kg. Increasing the fish meal level significantly improved feed utilization but only non-significantly increased daily gain. The lysine level had no significant effect on any of the measured performance parameters, suggesting that in maize meal based diets at lysine levels above the basic level of 0,70%, other essential or non-essential amino acids may be considered limiting. The identification of such limiting amino acids is an important prerequisite for recommendations on the optimal inclusion level of fish meal and lysine in maize meal based diets for growing pigs.