Populations of golden shiners in Horseshoe Lake have varied tremendously during the years we have studied it. . The bluegill sunfish was native to the eastern US but has been introduced around the world as a pan fish It is now the most abundant fish in many warm water lakes and ponds in California, including Horseshoe Lake, California Park Lake, and the Teichert Borrow Pits. The largemouth bass was introduced to California as a warm water game fish and has been widely distributed within the state. Largemouths are exclusively carnivorous, eating anything that will fit into their mouths as long as it tries to get away. While they are the top aquatic predator in Horseshoe, they are still subject to predation by large interface predators such as egrets, herons, and anglers.
White crappies are common in Horseshoe Lake.
They are thin, deep-bodied fish, with large delicate mouths. They have long, fine gill rakers which enable them to filter out zooplankton as a major source of food, but larger ones also take small fish. . Black crappies have also been introduced to the lake, but are less common. A black crappie's dorsal fin, measured along the base, is about the same length as the distance from the back of its eye to the front of its dorsal fin. A white crappie's dorsal fin is distinctly shorter.