Behaviour during the pelagic larval stage of coral-reef fishes can strongly influence dispersal, yet little is known of behavioural ontogeny. Speed, orientation and vertical distribution of larvae of 4 coral-reef fishes ( ) across the size range. All but the smallest, slowest larvae had Reynolds numbers >1000, and so swam in an inertial environment. In situ speeds were 39 to 87% of critical speeds, and smaller larvae swam nearer to critical speed than larger larvae. Of the larvae 71 to 90% swam directionally, but neither percentage of directional individuals nor orientation precision increased with size. P. teira swam toward the southwest (offshore). Epinephelus species undertook ontogenetic changes in orientation. Neither orientation nor ontogenetic changes were found in L. malabaricus. Horizontal swimming can influence dispersal directly. Vertical distribution, which differed among species, can influence dispersal indirectly. P. teira became surface orientated, ascending 0.8 m per mm increase in length. L. malabaricus descended 0.5 m per mm increase in length. E. coioides ascended 0.4 m per mm increase in length. E. fuscoguttatus preferred greater depths, and lacked ontogenetic changes. The behaviours and their development show these larval reef fishes can influence dispersal in speciesspecific ways.KEY WORDS: Connectivity · Dispersal · Larva · Ontogeny · Development · Coral reef · Fish · Serranidae · Lutjanidae · EphippidaeResale or republication not permitted without written consent of the publisher