The tame ducks at Agua Caliente Park here in Tucson will fiercely compete for any tossed bread scraps, but they don't just face competition for food from the other ducks. The warm, murky waters at Agua Caliente are filled with a variety of fish, mostly large, aggressive, non-native cichlids and these Bluegill (Lepomis macrochirus). These hungry fish will rise up from the depths to greedily gulp up some of the duck food before the squabbling ducks can reach it.

Bluegill (Lepomis macrochirus) fish in the pond at Agua Caliente Park in Tucson

Bluegills are a popular game fish that can be recognized by their round, disk-like shape and the round, dark extensions on their gill flaps. These fish travel in schools, and besides scavenged bread scraps, they will also eat invertebrates and small fish.