The development of neural cell topography in the retinal ganglion cell layer was examined in a teleost, the black bream (Acanthopagrus butcheri). From Nissl-stained wholemounts, it was established that fish between 10 and 15 mm standard body length (SL) possess high cell densities throughout the dorso-temporal retinal quadrant, with peak cell densities located in temporal regions of the retina. However, in fish between 15 and 80 mm SL, a wide variation in the position of the peak cell density is revealed with the locations of the areae centrales (AC) ranging from exclusively temporal to periphero-dorsal retina. Fish larger than 80 mm SL always possess an AC located in the dorsal region of the dorso-temporal retinal quadrant. The topography of ganglion cells within the ganglion cell layer was determined by comparing the numbers of ganglion cells retrogradely-labeled from the optic nerve with the total population of Nissl-stained neurons (ganglion plus displaced amacrine cells) in a range of different-sized individuals. Ganglion cell topography was the same as that recorded for all Nissl-stained neurons. The feeding behavior of juveniles from metamorphosis to 80 mm SL was observed, where fish were given the choice of feeding on live food in mid-water (until 15 mm SL) or obtaining pellets from the surface or the bottom. A range of feeding patterns was recorded, with the smallest fish taking food from mid-water but individuals between 15 and 80 mm SL taking food either from the surface or the bottom or both. A correlation between the preferred mode of feeding and the position of the AC was found, such that those individuals feeding in mid-water or at the surface possess a temporal or intermediate (dorso- temporal) AC, whereas those predominantly feeding from the bottom possess a dorsal AC.

The topography of the neurons in the retinal ganglion cell layer of juvenile black bream Acanthopagrus butcheri changes during development. The region of high cell density, the area centralis (AC), relocates from a temporal (central) to a dorsal (peripheral) position within the dorso-temporal retinal quadrant. To ascertain whether the di¡erences in the position of the AC during development are related to feeding behaviour, we monitored ¢shes that were given a choice of food. A range of feeding behaviour patterns was recorded in individual ¢shes. The smallest ¢shes (8^15 mm standard length (SL)) took live food from the water column. Following weaning onto pellets, ¢shes exhibited a preference for taking food from either the substrate or the surface (but not both). When greater than 20 mm SL, a number of individuals then divided their time between surface and substrate feeding before all ¢shes became exclusive benthic feeders at a stage between 50 and 80 mm SL. Three individual ¢shes, for which behaviour patterns were categorized, were killed and the topography of the retinal ganglion cell layer analysed. A range of positions for the AC was found with the smallest ¢sh (12 mm SL) possessing a region of high cell density in the temporal retina. In a larger ¢sh (70 mm SL), feeding from both the substrate and the surface, the AC was found in an intermediate dorso-temporal position. The AC of a ¢sh (51mm SL) preferentially taking food from the substrate was located in a dorsal position.