Warmouth

Adult warmouth appear dusky, with a mottled brown, somewhat purplish coloration. The ventral surfaces are yellow, and the breeding male has a bright-orange spot at the base of the dorsal fin. Three to five reddish-brown streaks extend from the eyes, whose irises are reddish, a feature most pronounced in breeding males, with a red dot present on the otherwise black opercular flaps, outlined in yellow. It most commonly has three spines in the anal fin and 6 to 13 spines in the dorsal fin, with small teeth present on the tongue and palatine bones. These fish are typically 4 to 10 inches (10 to 25 centimetres) long, but can grow to over one foot (30 cm) in length, and reach 2.25 pounds (1.02 kg). The warmouth is occasionally confused with the rock bass (Ambloplites rupestris) or green sunfish (Lepomis cyanellus), both of which share its relatively large mouth and heavy body.

Warmouth are found throughout much of the south in the Mississippi River drainage, from the Gulf and Atlantic coasts and northward to the Chesapeake Bay, and westward throughout Texas to the Rio Grande, and northward into the Great Lakes Basin area. The warmouth is a highly aggressive and hardy fish, and they can live in ponds, lakes, rivers, and backwater streams and can often survive in streams with low oxygen levels where other species of sunfish cannot. The species exists with breeding populations in southern portions of Canada, and likely has existed there for many years prior to being detected.

The primary diet of the warmouth consists of insects, crayfish, and other fish. They are sight feeders, and can survive in polluted, low-oxygenated waters where other sunfish cannot, like rock bass. The largest factor affecting warmouth density and biomass in Florida's lakes is the availability of aquatic macrophytes, which allows the fish to ambush prey and use as areas to spawn. The primary diet of young warmouth is microcrustaceans and aquatic insect larvae, whereas larger specimens tend to mainly consume crayfish, freshwater shrimp, isopods, and other small fish. Their predators include larger fish, snakes, turtles, alligators, and birds.