A 73-day feeding experiment was conducted to evaluate the effects of d
ietary crude protein level on growth of Eurasian perch juveniles. Dete
rmination of the protein requirement of 2.9 g perch was performed with
six semi-purified diets containing crude protein levels ranging from
0 to 60%. Fish were held in three recirculated systems, each diet bein
g tested in triplicate, Significant differences in growth and survival
appeared among fish fed diets containing up to 30% crude protein and
fish fed diets from 40% crude protein and above. Three mathematical mo
dels (the four parameter saturation kinetics, broken line and second o
rder polynomial Brett model) were used to analyse the relationships be
tween dietary crude protein and specific growth rate, According to the
saturation kinetics and polynomial models, the optimum dietary crude
protein levels were 36.8 and 43.6%, respectively, Based on broken line
and polynomial models, maximum growth occured at 43.1 and 56.5%, resp
ectively, Endogenous protein losses of 2.9 g juvenile perch reached 1.
11 mg fish(-1) day(-1) at 23 degrees C.