The microdistribution of ten numerically dominant species in a fish community at a rocky
island in Lake Victoria was studied using invasive sampling. All were haplochromine cichlids.
The community was characterized by high fish densities and by a dominance of Aufwuchs feeders.
Species were non-randomly distributed, showing significant associations with water depth and
other topographic parameters. Species occupied unique positions in a network of recurrent
species groups. Niche partitioning through differential microdistribution was even more subtle
than that reported for Lake Malawi's rock-dwelling cichlids. Species-specific microdistribution
fitted qualitative predictions from ideal free distribution models with asymmetrical
interference competition for food. No evidence was found for interspecific contest competition
for space. Temporal niche shifts have been observed between periods of high and low water
levels. Owing to a combination of reduced habitat availability with niche expansion in most
species, niche overlap was larger during the low-water period.