The family's 37 species include many fish familiar to North Americans, including the rock bass, largemouth bass, bluegill, pumpkinseed, and crappies. All are native only to North America. Family members are distinguished by having from five to 13 dorsal spines, which are sharp bones in the dorsal fin. Sizes of most are in the 20 to 30 cm (7.9 to 11.8 in) range. However, some are much smaller, with the black-banded sunfish at just 8 cm (3.1 in) in length, while the largemouth bass is reported to reach almost 1 m (3.3 ft) in extreme cases.
The male of most species builds a nest by hollowing out a depression using his tail, then guards the eggs. Most sunfish are valued for sport fishing. They have been introduced in many areas outside their original ranges, sometimes becoming an invasive species.