The warmouth is a type of sunfish that is found mostly in the warmer waters of lakes, ponds, and marshy areas. Most warmouth are found near the bottom of these waters because they are bottom feeders. These fish normally have a yellow or olive-green color, and the males have red eyes during breeding season. For this reason, some people refer to this type of fish as the red-eye or red-eyed bream. Warmouth can grow to be as long as 1 foot (31 cm) and may weigh as much as 2.25 pounds (1 kg). The majority of these fish tend to look very similar to bass, and many fisherman who catch them mistakenly believe they have caught bass.
Warmouth fish are native to North America and may be found as far south as the Rio Grande in Mexico and as far north as Ontario in Canada. Most of these fish prefer bodies of water that have lots of mud and vegetation on the bottom so they can hide and search for prey without being seen. Adult warmouth typically eat smaller fish and mollusks, and their young normally feed on insects and zooplankton. Unlike many other similar types of fish, these fish can tolerate water that is polluted and low in oxygen, which is likely why they seem to be very prevalent in swamps and ponds.
The male warmouth fish creates the nest during breeding season, which typically occurs during the spring and summer months. In the nest, the female might lay as many as 50,000 eggs but usually not less than 4,000. The male fish fertilize the eggs and protect the nest during the incubation period. It takes only three days for the young to incubate and hatch out, and they normally stay in the nest area for roughly one week before leaving for good. Young warmouth reach sexual maturity typically by the time they are 4 inches (10 cm) long.
Warmouth have some natural predators, which include turtles, snakes, and large fish, as well as some land predators such as herons. Most of these fish live for up to eight or nine years in the wild, but they are considered a threatened species in Canada. Marshy areas in Canada are starting to disappear due to draining, and some measures are being taken to ensure the survival of this fish species. There are some of these fish that are currently living in protected conditions in various areas throughout Canada.