Substrate selection by fantail (Etheostoma flabellare ), greenside (E. blennioides ), and rainbow (E. caeruleum ) darters

The seasonal substrate preferences of fantail, greenside, and rainbow darters were examined in a laboratory stream tank. The fantail darter, tested singly or in the presence of congeners, exhibited a strong preference for the largest substrates (i.e., pebble, cobble-boulder) in all seasons. The percentage of observations of fantail darters on pebble and cobble-boulder substrates ranged from 44.3% to 71.1%. Of the three species examined, the greenside darter showed the greatest preference for the largest substrates. The percentage of observations on the pebble and cobble-boulder substrates for this species ranged from 52.1% to 73.9%. in Contrast to the other species, the rainbow darter used all substrates with approximately equal frequency. The results of similarity analyses revealed high levels of overlap (> 0.600) in substrate use among the three species in all seasons. However, interspecific differences in morphology, foraging method, and foraging area may reduce the potential for competition for space among these species.