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I assessed the relationship between growth of fish in situ, food consumption, prey type and fish community descriptors in 12 perch (Perca flavescens) populations exhibiting a 1.8 to 10-fold range in growth rates. / Perch growth rates consistently decreased as fish numerical density increased (r$ sp2$ = 0.60) and increased as feeding levels increased (r$ sp2$ = 0.30). I found no significant relationship between the quantity of food consumed by perch and fish numerical density. Prey quality explained from 50 to 95% of the observed variability in growth but was related to fish numerical density in only one of the 3 perch age classes studied. / I conclude that non-exploitative interactions (operating through increased activity costs) is a more viable explanation for the among-population variability in fish growth rates than is exploitative competition (yielding decreases in the total quantities of food consumed and/or prey quality).