The Orangespotted Sunfish

The Orangespotted Sunfish (Lepomis humilis) is often confused with other sunfishes. This species is classified in the class Actinopterygii, order Perciformes, and family Centrarchidae. One characteristic that makes them stand out from other fishes are their black and orange spots. Also, their operculum is lined with a solid white band. Nine to ten bars can be identified on this fish. The bars on the female have a light center, which is a way of gender identification when the males are outside of the breeding season and not brightly colored. Identification of species and gender is especially important when sampling fishes. During breeding season, males have a bright orange belly and metallic blue body while the females are much duller in color.
The males are brightly colored during breeding season to attract females. In order to make the nest, the males sweep with their caudal fin to form a small depression in the sand or gravel. They are the smallest nests of the sunfish. The male guards the nest until the offspring are able to swim and leave the nest. This spawning period takes place from June to August. They produce 175-4,700 eggs each season, which stick to the stones in the nest. Eggs hatch in about five days and mature within one year if they make it to that age. Nesting colonies are large and formed in littoral, shallow waters. The maximum size of an Orangespotted Sunfish is about 15 centimeters. Because this fish is so small, they are often abundant because they are rarely caught and not a focus of anglers. Also because of their small size, they are a food source for bass and catfish. Otoliths were used to discover the maximum age of these fish is four. They have an annual mortality rate of 55-70 percent, exemplifying that they do have predators. The majority of an Orangespotted Sunfish population are age two or three individuals with a length of five to six centimeters. This concludes that many young and very few older individuals contribute to the mortality rate and most of the fish are mid-age and mid-length.
Orangespotted Sunfish are lotic fish found primarily in rivers and reservoirs and are tolerant of turbid water. The muddy, slow moving water found in the Big Sioux River and the Cheyenne River is a common place to find these fish. They range throughout the Great Lakes, to Texas, and to Ohio. Orangespotted Sunfish are the sunfish most adapted to pollution and turbid waters of low-quality water, which is why they can expand their range widely while other sunfishes cannot as easily. They have expanded farther eastward since 1990 and across the entire state of Ohio. They obviously have a high enough survival rate to expand that far in that short of time. Also, the rivers provide a large connection for the sunfish to flourish. Orangespotted Sunfish are more abundant in pools than any other habitat like runs or riffles and prefer places where refuge is nearby. They will reside in pools, then scatter in fallen logs and in holes between rocks to take
cover. This is caused by the deep, compressiform body shape.
The compressifrom body shape is not as favorable for fitting into small spaces as the anguilliform, eel-like, style but with the small size of these fish and a larger amount and variety of refuge or cover found in rivers, they survive quite well. This compressiform body style allows this fish to make quick turns and short, fast bursts of speed with good maneuverability. The caudal fin is forked with a low aspect ratio meaning the tail is broad, the fish has good acceleration from the start, and the tail aids in hovering. A forked tail allows for good acceleration and maneuverability with a slight amount of drag. The dorsal fin has ten anterior spines that are directly connected to the rays of the posterior dorsal fin. Spines help protect this fish from predators and keep them balanced. The anal fin, outlined in black, also has three spines for extra protection. They have short and rounded pectoral fins which contribute to speed and allow the fish to fit into small crevasses. The primary swimming form of the Orangespotted Sunfish is labriform because they row their pectoral fins, an oscillatory fin motion. The mouth of these fish are terminal and moderately
large. A terminal mouth allows this species to be a benthic and surface feeder. Their gill rakers are long and slender with space between them. This allows for particles in the water that flow into the mouth of the fish that they do not want to eat, to flush out. It indicates that the food of this fish is medium to large sized compared to their body. This correlates with an omnivorous diet and the ability to consume small and large prey. Daphnia and Cyclops are crustaceans often found in this species’ diet. Also, they help with mosquito control by feeding on mosquito larvae. The eyes of the Orangespotted Sunfish are corrected for spherical aberration, meaning they are a visual fish and need sight to find their prey. Since their prey is small fish and crustaceans, good eyesight is important to find them in the murky water that they live in. The Orangespotted Sunfish has adapted traits to better thrive in it’s habitat.