This article introduces ‘‘Quirks,’’ a generic, individual-based model synthesizing over 40 years of empirical and theoretical insights into the foraging behavior and growth physiology of marine fish larvae. In Quirks, different types of larvae aredefined by a short list of their biological traits, and all foraging and growth processes (including the effects of keyenvironmental factors) are modeled following one unified set of mechanistic rules. This approach facilitates ecologicallymeaningful comparisons between different species and environments. We applied Quirks to model young exogenouslyfeeding larvae of four species: 5.5-mm European anchovy (Engraulis encrasicolus), 7-mm Atlantic cod (Gadus morhua), 13-mm Atlantic herring (Clupea harengus), and 7-mm European sprat (Sprattus sprattus). Modeled growth estimates explainedthe majority of variability among 53 published empirical growth estimates, and displayed very little bias: 0.65%61.2% d21(mean 6 standard error). Prey organisms of ,67% the maximum ingestible prey length were optimal for all larval types, interms of the expected ingestion per encounter. Nevertheless, the foraging rate integrated over all favorable prey sizes washighest when smaller organisms made up .95% of the prey biomass under the assumption of constant normalized sizespectrum slopes. The overall effect of turbulence was consistently negative, because its detrimental influence on preypursuit success exceeded its beneficial influence on prey encounter rate. Model sensitivity to endogenous traits andexogenous.