As bottom feeders, their preferred food is snails, yet they likewise consume various other shelled animals. Their thick, tough teeth permit them to crush the skeletons of shelled pets. These teeth go to the rear of their mouths, as well as allow them to operate like a nutcracker by crushing the coverings of snails, for this reason the nickname, "shellcracker". They could even open tiny clams. They will additionally consume larvae, fish eggs, and also crayfish. As a result of its specific food particular niche, Redear sunfish can stay in lakes without contending for the same food of fish that like area feeding. And also since snails can spread illness, as well as considering that snails are among Redear's preferred meals, these fish are made use of in lake management projects to manage snails.
Redear sunfish spawn from springtime to early autumn. The men develop nests in silt, sand, or soft mud. These nests are constructed with each other in swarms in shielded, shallow areas near the coast. The girls transfer the eggs which hatch out within two to four days. These eggs are guarded by the men for many days. The young live on zooplankton.