Warmouth
The Warmouth sunfish is native to the United States, from Minnesota to western Pennsylvania in the north and from the Rio Grande in New Mexico east to the Atlantic in the south. The name originated from the stripes around its mouth resembling war paint.  Warmouths are easily identified and distinguished from other sunfish by their large mouths. These smallish sunfish (6-8 inches) have the body of a bream and the head of a bass. Warmouths are rather aggressive, often striking at lures and baits even after being recently released moments before.
 
These sunfish prefer heavily vegetated, muddy-bottomed ponds and streams. Aquatic vegetation, stumps and snags, and under the banks of streams and ponds are attractive haunts for them to ambush prey. Their tolerance for muddy water is higher than most species. The similar looking rock bass is rarely found living in the same habitat as the warmouth sunfish.
 
Spawning occurs in late spring.  Nests are made over aquatic vegetation and as it is with other sunfish, the males guard the eggs until the fry hatch. Chasing off intruders with gill covers spread wide and mouth open by making himself appear larger. Most live six to seven years.
 
Small freshwater are an important food source. Other prey items include small crayfishes, aquatic insect larvae, and minnows. Feeding occurs primarily in the low light hours of morning and evening.

Description
The warmouth is somewhat larger than either rock bass or green sunfish (with which it is often confused) but very similar otherwise in that it is large-mouthed and heavy-bodied. Adult warmouth are dark, with mottled brown coloration. Their belly is generally golden, and males have a bright orange spot at the base of the dorsal fin. Three to five reddish-brown streaks radiate from the eyes, and the gill flaps are often red. Warmouth have three spines in the anal fin, 10 spines in the dorsal fin, and small teeth are present on the tongue. These fish range in size from 4 to10 inches (10.2 to 25 cm), but can grow to more than 12 inches (31 cm), and weigh up to 2.25 pounds (1 kg).

Life History
Young warmouth feed on zooplankton and small insects. Adults feed on insects, mollusks, and small fish. Their predators include larger fish, water snakes, turtles, and herons. Warmouth reach sexual maturity at 3 to 4 inches (7.5 to 10cm), and spawn in the spring, when water temperatures reach 71° F (21.5° C), and continuing through the summer. Males construct a disc-shaped nest by fanning their tails and removing silt and debris over nesting site. Nests are made in 1.5 to 4 feet (0.45 to 1.23 m) of water near a stump, clump of vegetation or other large, submerged object. Females produce 4,000 to 63,000 eggs during spawning season. After an incubation period of three days, the young hatch. The fry leave the nest five to six days after hatching and grow to 1 to 2 inches (25.4 to 50.8 mm) by the fall. Their life span is not known.

Warmouth are quite secretive. They seek cover in rocky banks, stumps or weeds, or near other large objects, where they can hide and wait for food. They are sight feeders. When in breeding condition, the males' eyes turn red. After the female lays her eggs, the male fertilizes the eggs and aggressively defends the nest, eggs and fry from any intruder-including other females. Warmouth hybridize (crossbreed) with bluegill and green sunfish. They can survive in polluted, low oxygenated waters where other sunfish cannot. Warmouth are often confused with rock bass. The difference between the two is in the anal fin: warmouth have three spines on the anal fin ray and rock bass have six spines.

Habitat
Lakes, ponds, swamps, and quiet areas of streams with muddy bottoms and vegetation are preferred habitat for the warmouth.

Other
Warmouth are members of the sunfish family, which includes the largemouth bass. They are also known by more colorful local names such as redeye, goggle-eye, red-eyed bream, stump knocker, mudgapper, mo-mouth, morgan, molly, rock bass, open mouth, weed bass, wood bass, strawberry "perch" and mud bass. Because warmouth hit hard and are easily caught, they are popular with some anglers. They are good to eat when caught in clean water, but because they are bottom-feeders like catfish, the flesh can have a strong flavor.

Courtesy of Texas Parks and Wildlife