Lepomis microlophus

Geographic Range

Redear sunfish are native to the central and southern United States and can be found in the St. Lawrence-Great Lakes and Mississippi River drainages, as well as the Atlantic and Gulf Slope drainages. Redear sunfish have been introduced as game fish throughout the United States, as well as in Morocco, South Africa, Panama, and Puerto Rico.

• Biogeographic Regions
• nearctic nearctic
  • introduced introduced
  • native native
• palearctic palearctic
  • introduced introduced
• ethiopian ethiopian
  • introduced introduced
• neotropical neotropical
  • introduced introduced

Habitat

Redear sunfish prefer warm and calm or stagnant waters. As a result, preferred habitat is restricted to ponds, lakes, river backwaters, and reservoirs. The riverine habitats in which they are found, tend to be large and slow flowing with moderate amounts of aquatic vegetation. Redear sunfish are mainly found in water that is at least 2 m deep. They commonly live in low salinity waters (less than 4 ppt) but have been found in waters with salinities as high as 12 ppt.

• Habitat Regions
• temperate temperate
• tropical tropical
• freshwater freshwater

• Aquatic Biomes
• lakes and ponds
• rivers and streams

• Wetlands
• marsh marsh

Physical Description

Redear sunfish have laterally compressed bodies that are green, grey, or black. They can be distinguished from other sunfish via 3 different characteristics: 1) the red or orange margin on the opercular flap, 2) cheeks without conspicuous orange and blue streaks, and 3) pectoral fins that are greater than a third of the length typically found in sunfish. They often have small green specks on their heads and grey or black specks covering their bodies. Their pectoral fins have 13 to 14 pectoral rays, which taper to a terminal point. Their dorsal fin has 10 to 11 spines, and the anal fin has 3 spines. The terminal end of the opercular flap is marked by a large black spot, accompanied by two smaller white spots. The brightly colored terminal margin on the opercular flap is red in males and orange in females. At sexual maturity they are approximately 224 mm and can weigh as much as 454 g.

Redear sunfish are similar in appearance to their close relative, pumpkinseed sunfish ( Lepomis gibbosus ). As a result, the two species are often confused for one another. However, pumpkinseed sunfish have a number of wavy iridescent lines along the check and opercular flap that are not present in redear sunfish.

• Other Physical Features
• ectothermic ectothermic
• heterothermic heterothermic
• bilateral symmetry bilateral symmetry

• Sexual Dimorphism
• sexes colored or patterned differently

Development

Optimal incubation temperatures for redear sunfish eggs range from 22°C to 24°C. Incubation normally lasts 50 hours. After hatching, fry hide in gravel nests until about 3 days after hatching. Juveniles stay close to aquatic plants for protection and at 1 year old, leave the protective cover of aquatic plants to prey on open-water snails.

Growth rates appear to be dependent on turbidity as redear sunfish grow more rapidly in less turbid water. Different age classes can be identified according to size. First year fish range from 50 to 100 mm in total length (TL), and second year fish range from 110 to 140 mm TL. Fish that are 5 to 6 years old range from 200 to 250 mm TL.

• Development - Life Cycle
• indeterminate growth indeterminate growth

Reproduction

During mating season, male redear sunfish make popping sounds while in close proximity to females, which are used to gain the attention of potential mates. During courtship, males repeatedly surge toward potential mates while making popping sounds, which are made by clapping the jaws shut. Males also gain the attention of females via chemical and visual cues.

Male redear sunfish construct nests made from sand, gravel, and mud. Nests are typically found near aquatic plants, which provide cover for juveniles prior to maturation. Nests are approximately 25 to 61 cm wide and occur anywhere from 1 to 6 m deep. After fertilization, males do not leave the nest until all their eggs have hatched. Female sunfish lay their eggs in several nests each mating period.

• Mating System
• polyandrous polyandrous

Redear sunfish mate once per year. The start of spawning season depends on water temperature, with warmer temperatures resulting in earlier spawning. Spawning typically occurs in shallow water at temperatures between 21°C and 24°C. Spawning begins in early spring and ends in mid-summer but may extend into early October in warmer climates. Maturation rates are also dependent on climate, as individuals start to spawn at 1 year old in warmer climates and at 2 years old in colder climates. Finally, female sunfish produce between 9,000 and 80,000 eggs per mating season.

• Key Reproductive Features
• iteroparous iteroparous
• seasonal breeding seasonal breeding
• sexual sexual
• fertilization fertilization
  • external external
• oviparous oviparous

Male redear sunfish build nests prior to spawning and protect their nest for up to 3 days after spawning.

• Parental Investment
• male parental care male parental care
• pre-fertilization
  • protecting
    • male
• pre-hatching/birth
  • protecting
    • male
• pre-weaning/fledging
  • protecting
    • male
• pre-independence
  • protecting
    • male

Lifespan/Longevity

Redear sunfish have an average lifespan of 6 years. The oldest wild-caught redear sunfish was 8 years old at time of capture. In captivity they can live to be 7 years old.

Behavior

Redear sunfish that share habitat with largemouth bass ( Micropterus salmoides ) and bluegill ( Lepomis macrochirus ) are forced to compete for food as fry and juveniles. They eat insect larvae until their jaws are strong enough to crush the shells of their primary prey, aquatic snails. Once their jaws are strong enough, competition for food decreases due to an abundance of snails. Redear sunfish are crepuscular and tend to rest during the day.

• Key Behaviors
• natatorial natatorial
• crepuscular crepuscular
• motile motile
• sedentary sedentary
• territorial territorial
• social social

Home Range

Little is known about the home range of redear sunfish. However, their close relatives, bluegill and pumpkinseed sunfish , have home ranges of about 0.5 ha and 1 ha, respectively.

Communication and Perception

Redear sunfish use several modes of communication. It has been suggested that Lepomis species use chemical cues during nest building. During spawning, redear sunfish swim in a circular pattern around their mates. Males produce a popping sound to induce egg laying in females, which they produce by clapping the jaws shut. Finally, females select mates, at least in part, based on the pattern and intensity of a potential mate's coloration.

• Communication Channels
• visual visual
• acoustic acoustic
• chemical chemical

• Perception Channels
• visual visual
• tactile tactile
• acoustic acoustic
• chemical chemical

Food Habits

Redear sunfish are mainly bottom feeders. Fry stay in benthic waters and feed on algae and microcrustaceans. Juveniles eat insects, insect larvae, and small snails. Once their jaws fully develop, usually at about 1 year old, they begin to feed exclusively on snails. Adults feed on snails, aquatic insects, copepods, and organisms with hard shells, such as crustaceans. Evidence suggests that redear sunfish prefer snails with moderate shell thickness, as opposed to thin or thick shelled snails.

• Primary Diet
• carnivore carnivore
  • molluscivore molluscivore

• Animal Foods
• insects
• mollusks
• aquatic or marine worms
• aquatic crustaceans
• zooplankton zooplankton

• Plant Foods
• algae

Predation

Redear sunfish have several predators, including humans ( Homo sapiens ). They are considered a sport-fish species and are stocked in many lakes and streams. Humans commonly consume them and their larvae are prey to many other sport-fish species, including largemouth bass ( Micropterus salmoides ) and catfish (Genus: Ictalurus ). Redear sunfish avoid predation by retreating to shaded areas and deeper waters. Redear sunfish carcasses are often scavenged by birds and raccoons ( Procyon lotor ).

• Anti-predator Adaptations
• cryptic cryptic

Ecosystem Roles

Introduced redear sunfish have significantly impacted native fish populations. For example, when introduced into habitats occupied by pumpkinseed sunfish ( Lepomis gibbosus ), pumpkinseed populations significantly declined. Redear sunfish have strong jaws, which allow them to crack mollusk shells more easily than pumpkinseed sunfish can. As a result, redear sunfish likely decrease food availability for pumpkinseeds.

Redear sunfish are host to the non-native parasitic copepod, Neoergasilus japonicus . Neoergasilus japonicus attaches to the outer surface of its host, likely feeding on the dermal tissue underlying the scales. Gut content analysis, however, shows that the primary diet of free-swimming N. japonicus consists primarily of blue-green algae.

Economic Importance for Humans: Positive

Redear sunfish are considered a sport fish and are regularly consumed throughout United States.

• Positive Impacts
• food food

Economic Importance for Humans: Negative

There are no known adverse effects of redear sunfish on humans. However, when redear sunfish populations are introduced to non-native waters, they may negatively affect the ecosystem and out-compete native fish species. This may affect the fishing industry and overall health of ecosystems that humans depend on for food and water.

Conservation Status

Redear sunfish exhibit stable population trends throughout its range and are in no danger of decline.

Additional Links

Encyclopedia of Life

BioKIDS Critter Catalog

Contributors

Jacob Barbee (author), Radford University, Karen Powers (editor), Radford University, John Berini (editor), Animal Diversity Web Staff, Tanya Dewey (editor), University of Michigan-Ann Arbor, Renee Mulcrone (editor), Special Projects, Rachelle Sterling (editor), Special Projects.

References

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