Baby Black Bullheads (Ameiurus melas)

A local office building's ponds were full of tiny black bullheads in mid-June. None of these fish was more than 2 inches (5cm) long. At any given moment, a dozen schools of 100-300 fish were visible, along with giant tadpoles. June 16, 2015. Westchester, IL.
(Also at https://flic.kr/p/zPNHCu)flickr