Sunfishes (Lepomis) of Virginia, by Don Orth

Centrarchid fishes exist only in North American freshwaters and are well known as popular sport and aquarium fishes.  There are 38 species in eight genera, all of which may be identified by a laterally compressed body, two connected spiny and soft dorsal fins, spines on anal fins, and pelvic fins in a thoracic position.  The most diverse genus is Lepomis, commonly referred to as the sunfishes in recognition of their highly colored breeding colors.  These colorful sunfish are often the first fish caught and remembered by a young angler.  Their importance in sustaining American sport fisheries cannot be overstated.    Virginia has eight species of Lepomis, but there are thirteen in North America (Warren 2009).  Explore this link to a gallery of photos of Lepomis.  

Due to the popularity as a sport fish, sunfish are widely introduced throughout North America and even in other continents.  The body form and habits all support a generalized sight-feeding habit on a variety of crustaceans, insects, and small fishes. Males develop bright breeding coloration, establish territories, and build shallow, circular nests. Nests may be solitary or colonial and males aggressively defend their nest, court females, and guard eggs and young.  Closely related species have a tendency to hybridize, complicating the identification.  Because of the high fecundity and parental guarding behavior, many young sunfish are produced and become prey for numerous sport fish and other aquatic predators, such as water snakes Nerodia, snapping turtles Chelydra serpentina, and hellbenders Cryptobranchus alleganiensis. 

Male sunfish guarding a circular, depression nest.  Photo by Alan Creech.  Creative Commons

The male nest construction and guarding and courting behaviors are well studied and all species of Lepomis demonstrate similarities in breeding.  The breeding male excavates a circular depression and defends the territory against all intruders.  This is a great time to get up close and personal with a male sunfish because they are so reluctant to flee.  See this photo of a beautiful male sunfish made possible because it was defending a nest.  During nest defense, the male sunfish displays to nearby or approaching males and females with a behavioral repertoire that consists of  nest hovering, dashes to the water surface and back to the nest, nest sweeping with caudal fin, fin spreading, mouth gapes, jaw snaps, lateral displays, substrate biting, and opercular spreads.  Rim circling behaviors where the male rapidly swims around the edge of the nest with fins erect are intended to attract a female. Opercular flaring is directed at females and apparently signals to the female the species, condition, and quality of the breeding male.  Males also use sounds to court mates.  If the female follows, the male performs courtship circles, encircling the female and leading her to the nest. The size of the male earflap is a key determinant of dominance in a hierarchy. 

Here are the eight species of sunfishes of Virginia.  

Redbreast Sunfish Lepomis auritus is native to the Atlantic slope drainages of Virginia but is now well established in all Virginia waters, except some acidic swampy drainages.  This sunfish has a moderate size mouth  with the upper jaw extending to the anterior edge of the eye.  Body is olive on the back and sides with yellow orange spots on the side and an orange breast.  Iridescent blue wavy lines radiate from the mouth across the snout and onto the cheek and opercle.   The ear flap is narrow and elongate, dark to the posterior margin. 

Redbreast Sunfish Lepomis auritus. Photo by Noel Burkhead.  Source

Green Sunfish Lepomis cyanellus is a very common and spunky sunfish that may occur in streams, rivers, ponds, and shallow weedy margins of lakes. The body shape is not as deep and the mouth is large. The coloration is blue green on back and sides with reflections of yellow and emerald.  The cheeks have distinctive blue wavy streaks.  The ear flap is black with white or yellow orange margins and is not elongated or flexible as in some other sunfish.  Black blotches are usually present near the base of soft dorsal and anal fins.  The pectoral fin is rounded and, when bent forward, will not extend beyond the front of the eye.  The fringe of white, yellow and/or orange along the fins develops in breeding males.   

Green Sunfish Lepomis cyanellus.  Photo by Nate Tessler

Pumpkinseed Lepomis gibbosus seem to prefer vegetated streams, ponds, and reservoirs.  Pumpkinseeds have wavy blue lines on the cheek and opercle.  The opercular flap is short and stiff with a black center, bordered by a semicircular spot on the posterior edge.  This spot may be white, pale yellow, or red.  The pectoral fin is long, and sharply pointed. When bent forward, the pectoral fin will reach beyond the front of the eye.  Pumpkinseed have specialized molariform teeth in their throat, used for crushing snail shells.  

Pumpkinseed Lepomis gibbosus.  Photo by Olaf Nelson.  Creative Commons

Warmouth Lepomis gulosus occur in vegetated lakes, ponds, swamps, reservoirs, and sluggish habitats in streams.  Warmouth has a large, terminal oblique mouth with lower jaw projecting slightly past the upper jaw.  Three to five dark red bands radiate from the snout.  The opercular flap is short and stiff, and black with paler often red-tinged border.  The coloration is olive brown with dark brown mottling on back and side and dark spots and bands on fins.  The pectoral fin is short and round, usually not reaching the eye when laid forward.  Breeding males (pictured below) are boldly patterned with a red orange spot at the base of the second dorsal fin and black pelvic fins.  

Warmouth Lepomis gulosus.   Photo by Olaf Nelson.  Creative Commons

Bluegill Sunfish Lepomis macrochirus occupy all types of lacustrine and fluvial habitats.  Bluegill have a small mouth.   They have a large black spot at posterior end of soft dorsal fin.   Opercular flap is moderate or long and flexible with black margins. Coloration is blue with dark chain-like bars along the side, which may be absent.  Adults will have two blue streaks from the chin to the edge of the gill cover.   Pectoral fin is long and pointed.     

Bluegill from Lake Lanier, Georgia.  Creative Commons

Hybrid Bream -- The hybrid between the Bluegill Sunfish and the Green Sunfish is commonly produced and marketed for stocking in farm ponds.  The F1 has desirable traits such as enhanced growth and reduced fertility.  The photo below is a hybrid that has blue cheek lines of the Green Sunfish and chain-like bars of the Bluegill. 

Hybrid Bream.  Photo by MSU Extension Service/Wes Neal

Dollar Sunfish Lepomis marginatus occur only below the fall line and inhabit swamp-like habitats in low gradient streams and beaver ponds.  They are the smallest Lepomis in Virginia, and max out at only 4 inches.  The mouth is small and there are wavy blue lines on cheek and opercle.  The opercular flap is long, flexible, black in the center and edged with lighter margins.  Coloration is dark red on back and bright orange on the belly with many blue spots on the side.    

Dollar Sunfish Lepomis marginatus  Photo by Derek Wheaton

Longear Sunfish Lepomis megalotis  inhabits pools of headwaters, creeks, and small to medium sized rivers.  Longear Sunfish have distinctive wavy blue lines on snout, cheek, and opercle.  The opercular flap is long and flexible with a black center and shite edges of equal with.  the pectoral fin is short and rounded, not reaching the eye when laid forward.   Adults are dark red above, bright orange below, and marbled and spotted with blue on the side.  Longear Sunfish vigorously attach a variety of baits and is frequently caught with spin and fly fishing.  

Longear Sunfish  Lepomis megalotis.  Photo by Brett Albanese, Georgia DNR

Redear Sunfish Lepomis microlophus inhabits ponds lakes and reservoirs and sluggish pools and backwaters of rivers. Redear Sunfish resemble Bluegill. They do not have wavy blue lines on the head.  The opercular flap is short, with black center  and bordered above and below in white margins and posteriorly with a prominent red or orange crescent.  Coloration is light gold green above with many dark connected spots on the side.  Pectoral fin is long and pointed.     It is widely stocked for sport fishing and eats snails and small bivalves, earning it the name "shellcracker."  Anglers catch Redear Sunfish with worms and other natural baits fished near the bottom.  

Redear Sunfish  Lepomis microlophus.  Photo by Kentucky Dept. of Fish & Wildlife Resources.

The fascinating sunfishes Lepomis spp. are North American treasures.   They are easy to catch, fun to watch, good to eat, and provide many opportunities for education and scientific study.   In addition to the Lepomis spp., other centrarchid fishes include the include Mud Sunfish (Acantharchus pomotis), Flier (Centrarchus macropterus), two rock basses (Ambloplites), three banded sunfishes (Enneacanthus), two crappies (Pomoxis),  and three black basses (Micropterus).    

Catching sunfish makes young ones happy.  Photo by Joseph Bartmann.  Creative Commons

Reference

Warren Jr., M.L., 2009.  Centrarchid identification and natural history.  Pages 375-533 in S.J. Cooke and D.P. Philipp, editors. Centrarchid fishes: Diversity, Biology, and Conservation.  Blackwell Publishing, Ltd., United Kingdom.

 

Green Sunfish Is One Tough Sparring Partner, by Don Orth

Green Sunfish (Lepomis cyanellus Rafinesque) is a very common sunfish that may occur in streams, rivers, ponds, and shallow weedy margins of lakes.  No matter where you find them, they will usually be in close proximity to weedy vegetation, large boulders, or woody cover.   Although their maximum size may not be very impressive, they make up for the small size with spunk.   The world record Green Sunfish  was 2 pounds, 2 ounces – that must have been one big spunky sunfish.   The generic name is derived from Greek words that refer to the scales on the operculum, while the species name is derived from the Greek word for blue, in reference to the blue wavy lines on the cheeks. 

 

Green Sunfish adult. Photo by Nate Tessler.  Source. 

To positively identify a Green Sunfish you will have to check a number of characteristics.   Coloration is bluish-green on back and sides with reflections of yellow and emerald.  Blue wavy streaks are present on the cheeks.   The belly is pale yellow or white. The ear flap is black with a white or yellow-orange margin; it is not elongated and the bony margin of the gill cover is hard and inflexible.   Black blotches are usually present near the base of soft dorsal and anal fins.  The body is not as deep bodied as other Lepomis.   Body depth is approximately equal to the distance from the tip of the snout to the origin of the dorsal fin; measure to be sure!  It has a large mouth for a sunfish with the upper jaw extending to the middle of the pupil.   The pectoral fin is rounded and, when bent forward, will not extend beyond the front of the eye. Juveniles and hybrids can be more challenging to identify.  Green Sunfish have a complete lateral line with 41 to 52 scales, which is intermediate between Micropterus and other Lepomis.   When breeding, the male Green Sunfish develops fringes of white or salmon or yellow on the dorsal, caudal, anal, and pelvic fins.   Females and subordinate individuals will not develop the fringes and have a dorsal ventral banding pattern. 

 

Juvenile Green Sunfish.  Photo by Dan Johnson.  Source

Why the opercular ear flap?  All Lepomis sunfishes have a dark ear flap.   Why the spots on the soft dorsal fin?   Only Bluegill, Bantam Sunfish, and Green Sunfish have the blotches.  Think about it! 

Green Sunfish is tolerant of a wide range of environmental conditions. Therefore, it is often found in sloughs and ditches where no other sunfish is present.  It is usually one of the few sunfish that will persist in small streams of the Great Plains along with Creek Chubs Semotilus atromaculatus, Fathead Minnows Pimephales promelas, and Black Bullheads Ameirus melas.  Because of their broad geographic distribution and wide environmental tolerance, the index of biotic integrity in the Midwest USA has a Green Sunfish metric (Metric 6, Proportion of individuals as green sunfish).    That always seemed  speciesist, and the meaning of metric 6 should reflect proportion of highly tolerant fish.    Some streams are naturally harsh and the Green Sunfish is able to persist in harsh environments.    That should not influence the assessment of biological impairment.  Harsh places are not necessarily impaired.   However, Green Sunfish have become widespread outside its native range where they may suppress native fishes (Fuller et al. 2016). 

 

Distribution of Green Sunfish (Fuller et al. 2016)  USGS

The Green Sunfish seldom get large enough to attract the following of recreational anglers.  However, it is usually so common, especially in intermittent creeks, that it is a good fish for young anglers to target.  Green Sunfish provided me many an evening meal while camping during my dissertation research studies on Glover River, Oklahoma.  Here the Green Sunfish was the dominant fish species, comprising 46% of total biomass (Orth and Maughan 1984).    Green Sunfish are also popular as an aquarium fish for the native fish enthusiast because they feed readily and may persist under less than ideal water quality conditions.   

Sunfishes are notorious for hybridizing in nature.  Many species overlap in range, spawning time, and share limited nesting habitats.  More than 20 Lepomis hybrids have been reported in nature (Childers 1967). Natural hybrids are produced when one species at very low abundance and females of rarer Lepomis breed with an aggressive male of the dominant species (Avise and Saunders 1984).   These F1 hybrid exhibit adult sex ratios strongly biased toward males and, consequently, hybrid sunfish have been bred specifically for pond stocking.  The Green Sunfish x Bluegill cross is popular. Click here for photo of the F1 hybrid and parentals.  

 Green Sunfish show homing tendencies and defend territories as do other sunfish and Micropterus basses.   A territory is “any defended area,” and the Green Sunfish is an aggressive defender of their territory.   Bernard Greenberg first wrote about territoriality and social hierarchies in the Green Sunfish.  Hierarchies developed in groups of immature Green Sunfish only 0.75-1.5 inches standard length and less than one year old.   Establishing a dominance hierarchy early in life avoids wasting energy on agonistic display patterns.  Rather the dominant individuals “drive their subordinates, that is, they make quick dashes at them, and the latter swim away, usually without being nipped”  (Greenberg 1947, p. 269).    Green Sunfish show three aggressive behaviors: (1) gill-flare threat display; (2) weaving; and (3) nipping.  Green Sunfish pairs will occasionally test one another by a gill flare display.   The gill flare threat involves “spreading their gill-covers and moving head-on toward each other; the threatened individual turns broadside and, with body held rigid, vibrates in a weaving fashion” (Greenberg 1947, p 270).  The gill flare shows the observer the margined patch of black of the opercle flap, which roughly resembles an eye.    View the video of a Green Sunfish showing the gill flare display and you will see how effective this display. 

Video of Green Sunfish gill flare display.   by CarpGuy  Source

The spot on the soft dorsal fin also darkens when the Green Sunfish is interacting with another.   Greenberg observed that the fighting individual “almost always has these spots intensified, but, if it loses the fight, the spots disappear.”     Although many others have described aggressive behavior and territorial defense and displays, the experiments of Bernard Greenberg established that the Green Sunfish engaged in aggressive behavior and defend territories long before they became reproductively mature.

Greenberg also observed changes in the coloration of the eye during agonistic encounters.  The iris is normally red.  Hence the Green Sunfish is sometimes referred to as a goggle eye.   However, when Green Sunfish are fighting the red becomes more prominent.  In a Green Sunfish that loses in an encounter the black pigment spreads to the rest of the iris and the red is obscured.  Consequently the black eye signals a sign of defeat in the Green Sunfish.  

Close up of head of Green Sunfish.  photo by BluegillFishing.net.  Source.

The fighting pattern of two Green Sunfish involves one individual on the attack with gills flared and the other weaving to avoid being nipped.  The attacker may make a series of vigorous nips at the head or body and may even lock jaws.    In aquaria,    groups of Green Sunfish establish a pattern of dominance within 24 hours. Individuals learn to display subordinate patterns.   Further maze experiments by Greenberg supported the notion that dominant individuals in groups facilitated learning among members.   In an experiment comparing Green Sunfish in isolation and in groups, the individuals in groups grew faster over the period of study (Allee et al. 1948).  Reasons for enhanced growth are difficult to establish, although the authors did observe fish in social groups displaying more ready feeding.   Also, the high ranking fish within a social hierarchy ate more and grew faster than low ranking ones.

The Green Sunfish is an excellent example of a common opportunistic sunfish species that has a rich set of social interactions that have not yet been fully explored.  What you may see as aggressive interactions in aquaria are adaptations that will facilitate group success and resource distribution in wild populations.  Also, Green Sunfish have double cones in their eyes that make them sensitive to polarized light (Cameron and Easter 1993).  The adaptive significance of polarized light sensitivity has yet to be explored.  We can only speculate and devise new experiments. 

References

Allee, W.C., B. Greenberg, G.M. Rosenthal, and P. Frank.  1948.  Some effects of social organization on growth in the Green Sunfish Lepomis cyanellus.  Journal of Experimental Biology 108:1-19.

Avise, J. C., and N.C. Saunders. 1984. Hybridization and introgression among species of sunfish (Lepomis): Analysis by mitochondrial DNA and allozyme markers. Genetics 108:237-255.

Cameron, D.A., and S.S.Easter.1993. The cone photoreceptor mosaic of the green sunfish, Lepomis cyanellus. Visual Neuroscience 10:375-384.

Childers, W.F. 1967. Hybridization of four species of sunfishes (Centrarchidae).  Bulletin of the Illinois Natural History Survey 29:159-214.

Fuller, P., M. Cannister, and M. Neilson. 2016. Lepomis cyanellus. USGS Nonindigenous Aquatic Species Database, Gainesville, FL.
http://nas.er.usgs.gov/queries/FactSheet.aspx?speciesID=380 Revision Date: 1/20/2012

Greenberg, B.  1947. Some relations between territory, social hierarchy, and leadership in the Green Sunfish (Lepomis cyanellus).  Physiological Zoology 20:267-299.

Orth, D.J., and O.E. Maughan. 1984.  Community structure and seasonal changes in standing stocks of fish in a warm-water stream. American Midland Naturalist 112:369-378.