Northern Sunfish

Northern sunfish have 34–38 ctenoid scales along their lateral line. The pectoral fin of this species is much shorter and rounded than other sunfishes. The northern sunfish and longear sunfish are similar in appearance. Both are vibrantly-colored fish with distinct opercles. The opercle of L. peltastes tends to be steeply angled and stout, while those on L. megalotis are straighter and longer in comparison. Although each species display similar coloration, the patterns which form from these colors are different. The northern sunfish tends to have more distinct turquoise vertical barring than longear sunfish, the latter of which contains turquoise speckling or accents across the body. Some forms of longear sunfish appear much more red and orange than northern sunfish. Additionally, adult northern sunfish are typically smaller than longear sunfish, reaching a maximum total length around 12.7 cm (5.0 in). Age estimation with scales suggested the average maximum lifespan was four years, although a nine year old specimen was observed in Michigan.

Northern sunfish inhabit the northernmost portions of North America, such as the Saint Lawrence River and Great Lakes basins, as well as Hudson Bay, the upper Mississippi River, and portions of Ontario, Canada. Populations tend to be scattered within these areas. This fish is generally found in small, quiet, temperate streams or rivers. This species prefers vegetation and back bays where they can avoid strong currents. The northern sunfish is also found in the littoral zone of clear lakes. The simplest way to determine whether a longear sunfish is L. peltastes or L. megalotis is by range, although there is substantial overlap and introgression between these two species.

Much like longear sunfish, northern sunfish are omnivorous. They feed on aquatic and terrestrial insects, as well as other invertebrates such as mollusks and crustaceans. Stomach contents analyzed in Minnesota contained Gammarus spp., Trichoptera larvae, and Chironomidae larvae.