Summary
Relatively little work has been done on the ontogeny of feeding behaviour in fish. One of the aims of this study was to compare the ontogeny of feeding behaviour in four species of centrarchid fish of diverse feeding guilds. A second aim was to test Mayr's hypothesis that the locomotory acts involved in the ontogeny of feeding behaviour would be stereotyped. All four species initially displayed five feeding acts, with three of the acts disappearing from the repertoire at various intervals. The disappearance of the acts appeared to be related to the size and not to the age of the fry. The acts decreased in frequency as the fry aged and differences among the species in frequencies were minimal. The data supported Mayr's hypothesis but a modifying corollary was added to account for changes due to maturation.
Methodology
The study took place at the Queen's University Biological Field Station located on Lake Opinicon, Chaffey's Locks, Ontario, Canada. Fish were collected SS eleutheroembryos from a nest and immediately placed in separate wooden 90 glass-fronted tanks. All tanks were supplied with a continuous flow of lake water, 2c" and a natural photoperiod was maintained. Water temperature was within of ambient. A 2 cm layer of gravel covered the bottom and vegetation was added to each tank when the fry were six weeks of age. Densities of the fry in each tank were 150 per tank initially and were reduced, experimentally and by natural mortality, to 30 per tank by the end of the study. Free-swimming fry were fed cultured live zooplankton. Plankton collected from the lake were cultured in large pools and one bucket of the enriched water was added to each of the rearing tanks, three times per day (for details see Brown, 1983). The enriched water was monitored weekly to determine the taxa (to family) of zooplankton, and approximate percent occurrence of total. No attempt WSS made to regulate either the abundance or taxonomic composition of zooplankton fed to the fry. Preliminary observations indicated that fry of largemouth bass older than seven weeks did not survive well on the zooplankton diet, so their diet was supplemented with frozen brine shrimp. Only frequency data collected during the first six weeks for largemouth bass were used in the analysis.