Reduced disease in offspring: a benefit of coloniality in sunfish

Increased disease and parasitism are a well-documented cost of group living for colonial birds and mammals, but we now show that disease in offspring of fish may be reduced by nesting in colonies. The aquatic fungus Saprolegnia sp., which is a common cause of egg mortality among freshwater fishes, is more prevalent in the nests of solitary than colonial male bluegill sunfish (Lepomis macrochirus).