A rare and little-studied species, much of the boulder darter’s biology is, as yet, unknown. However, most darters are bottom-dwelling, diurnal fish that use sight to forage for immature insects, such as mayflies and stoneflies (4). These fish typically spawn between late May and early August, coinciding with a rise in water temperature to 18 to 23 degrees Celsius (2). The female boulder darter lays the fertilised eggs in a wedge-shaped cavity amongst large rocks in moderate to fast-flowing rivers. Once hatched, the juvenile fish alternate between resting on the bottom of the river bed and swimming, all the while feeding from an attached yolk sac. They will later become fully pelagic and will feed at the top of the water column on a variety of plankton (6).