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Warmouth (Lepomis gulosus)

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Department of Wildlife and Fisheries, Mississippi State University, Mississippi State, Mississippi, 39762, USA


Lepomis gulosus (Curvier 1829) is a sunfish commonly called the warmouth. It is a freshwater fish found throughout the eastern and southeastern portion of the United States. The warmouth are able to tolerate a variety of habitat conditions allowing them to survive in waters with low levels of oxygen and to thrive in areas of elevated salinity and temperature. They are omnivores and eat a variety of foods. No conservation concerns exist for the warmouth in the south or southeastern United States; they are vulnerable or imperiled in a few northern states. The warmouth are good laboratory fish, small-sport fish, and the cane-pole fisherman catches it for food.

  • Fig. 1. (Raver 2010) It is believed the warmouth name came from their: 1.Stripes resembling American Indian warpaint (Moyle 1978). 2.Aggressively hard strike, often breaking the surface of the water.
  • Fig. 2. (Haerer 2011) Warmouth Common Names: Perch mouth, Strawberry perch, Weed bass, Wide-mouth sunfish, Yawnmouth perch, Mudgapper, Jugmouth, Red-eye stumpnocker, Bigmouth, Indian fish, Sun trout, Wood bass, Goggle eye, Mud chub, Molly, Morgan
  • Fig. 3. (NatureServe 2013) Warmouth (Lepomis gulosus) U.S. Distribution by Watershed

Context & Content[+] Expand

Lepomis gulosus is from the Centrarchidae family, the second largest freshwater fish family of the Perciformes order (Table 1). Lepomis is the largest Centrarchid genus with 12 species: L. auritus, L. cyanellus, L. gibbosus, L. gulosus, L. humillis, L. macrochirus, L. marginatus, L. megalotis, L. microlophus, L. miniatus, L. punctatus, and L. symmetricus.

General Characteristics[+] Expand

The first and most obvious distinguishing feature of the warmouth is the redness of their eyes, particularly in breeding males (Becker 1983). This, along with a propensity to frequent stump fields, has earned them the nickname "red-eye stumpknocker" (Laerm and Freeman 1986). The warmouth is likely given its name because its stripes resemble the warpaint of American Indians (Moyle 1976). The fish's aggressively hard strike, often breaking the surface of the water is thought to be another reason for its name. Its large mouth extends to just beneath its large red eyes lending itself to many of its other nicknames. Some of the warmouth's common names are bigmouth, Indian fish, sun trout, wood bass, goggle eye, red-eye bream, mud chub, perch mouth, strawberry perch, weed bass, wide-mouth sunfish, yawnmouth perch, mudgapper, jugmouth, molly, and morgan (Ross 2001).
Warmouth have deep bodies which are compressed laterally, similar to bluegill. The adult warmouth have olive and mottled brown coloring, some have a purple tint and can change coloring to blend in with surroundings. Their ventral side is gold in color. They range in length from 10.2 to 25 cm long and can reach a typical weight of 1 kg, with the largest warmouth on record caught in Florida weighing in at 1.1 kg (FFWCC 2013). Their mouth is terminal and large. The upper jaw extends to the middle of the eye or farther with their lower jaw protruding noticeably beyond their upper jaw, similar to bass (Mettee et al. 1996). They have a well-developed pad of lingual teeth and patches of teeth on the palatine bones (Ross 2001). Warmouth also have teeth on their pterygoid (Hubbs et al. 1991; Hay 1894). They have sharp cone-shaped teeth on both upper and lower jaws as well as similar, but more rounded, teeth on their lower pharyngeal arches. On the side of their cheek, radiating from the eye and extending to the back of the gill cover are three to four posterior reddish-brown streaks (Etnier 1993). One to two anterior dark streaks radiates forward from their eye toward their mouth (Mettee et al. 1996).
Their supramaxilla bone's length is greater than the width of maxilla. The opercular bone is inflexible 'to back margin and will usually fracture if bent forward' (Ross 2001).

Distribution[+] Expand

Warmouth are naturally found in lentic or nearly lentic systems throughout much of the eastern United States from the Great Lakes basins south to Florida and west across the Gulf States to New Mexico (McMahon et al. 1984). They have also been introduced as far west as California; however, they are not native to the area. They prefer clear-watered lakes and large slow-moving streams with muddy bottoms and abundant aquatic vegetation for cover (ODNR 2013). They can also be found in the Everglades of Florida as well as other marshes in the southeastern US. (McMahon et al. 1984).

Form & Function[+] Expand

The warmouth is commonly confused with the green sunfish and the rock bass as they possess striking similarities in both mouth and body size. Warmouth are, however, generally larger than either of these (TPWD 2004). They are deep bodied and laterally compressed though not as much as a bluegill, being more compressed dorsoventrally and slightly less laterally. The warmouth also has three to four brown bars on its cheek and teeth on its tongue where the green sunfish and rock bass both lack this tooth patch (Ross 2001). The rock bass is also identified as having five to seven anal spines as opposed to the three to four spines on the warmouth (UWSGI 2013).
Warmouth have two dorsal fins, the first with 10 spines and the second with 9-10 soft rays; however, they are joined together and appear as one. The anal fin has 3-4 spines and 8-10 soft rays. The pelvic fin is thoracic, below the pectoral fin (Becker 1983). Fins have a darkly mottled appearance. Pelvic fins contain melanophores. There is no adipose fin. They have 36-40 lateral ctenoid scales (UWSGI 2013). The lateral line is complete and follows the anterior arch (Ross 2001).
Warmouth are easily sexed as the male warmouths are slightly larger than females and are marked with an orange spot at the posterior termination of the dorsal fin (Larimore 1957). They also have gold and/or light blue specks on their side. Breeding males will have more intense coloring with an increase in the golden yellow colors along with bright red eyes.

Ontogeny & Reproduction[+] Expand

They typically spawn in early spring; however, the breeding season of the warmouth begins in March and can run until September. They may spawn two or more times a season (Laerm and Freeman 1986). Unlike the other sunfish species, warmouth are solitary nesters. They do not spawn in colonies (ODNR 2013). The male warmouth will use his caudal fin to fan the area he wants the nest to create a bowl-shape nest. Their nest is built on gravel or rock in the shallows near the water's edge (Larimore 1957: Laerm and Freeman 1986). These nest sites are situated, almost without exception, in very dense cover (Laerm and Freeman 1986). Warmouth perform an intense courting ritual. The body of the male fish turns yellow and the redness of his eyes deepens in hue. The male and female fish swim together in the center of the nest. The female releases up to 63,200 eggs striking the male's face with her body in the process. It is believed that this action by the female signals the male to release his milt (Ross 2001). When spawning is completed, the nest is guarded by the male until the hatchlings are ready to leave the nest (Laerm and Freeman 1986). This usually occurs in a little over a week. After hatching, the warmouth fry grow at a rate of 38 mm per year, assuming the presence of adequate resources. They will become sexually mature in the second year of their seven-year lifespan (Laerm and Freeman 1986).

Ecology[+] Expand

Migration—Warmouth are typically a non-migratory species, traveling no more than 100 or so miles for spawning or wintering. According to O'Connell and Vrancken (2010), during the year following Hurricane Katrina, warmouth traveled approximately seven kilometers or 4.34 miles downstream from Bayou Lacombe where their habitat had been destroyed and increased debris had caused a decrease in dissolved oxygen levels. The warmouth requires an oxygen level of 3.6 ppm at 20 C but can survive for a short time in water with oxygen levels down to 1.0 ppm (Larimore 1957). Even though dissolved oxygen levels had remained fairly stable downstream, salinity levels and water temperatures were elevated and yet warmouth had migrated downstream and had created new habitat and had increased abundantly during the year following Katrina (O'Connell and Vrancken 2010). No warmouth were found upstream in the 2006 sampling.

Diet—The warmouth is an invertivore/carnivore and more than other sunfish, tends towards piscivory. It also feeds on aquatic insects and crustaceans (Cook 1959). At the larval stage the primary source of food consists of small crustaceans such as copepods, ostracods and cladocerans (Pflieger 1975). In a compilation of studies on warmouth 3.3-8.7 inches long, the warmouth's summertime diet consisted mainly of crayfish (Larimore 1957). The one autumn study performed on warmouth 3 inches, diet consisted mainly of fish and mayflies (Larimore 1957). In warm water warmouth may consume 4% of its body weight in food per day (Hunt 1960). Warmouth rarely feed at any time other than the early morning (Larimore 1957). This can render them more difficult to catch than other centrachids, though they will bite artificial lures readily as well as angleworms, minnows, white grubs or crickets (Cook 1959).

Behavior[+] Expand

Social and hierarchal behavior—Warmouth in a natural environment are not prone to congregating in schools and therefore have little social hierarchy (Wallus 2008). Many fish form groups in the winter but warmouth do not (Larimore 1957). Even though aggregation may occur around the warmouths' desire for similar cover or habitat and for a short period of time after hatching, they are typically an independent unsociable species (Wallus 2008).

Feeding behavior—The warmouth's feeding activities involve seeking cover in rocks, stumps or in aquatic vegetation where they hide and wait for prey to come by. They have a preference for the shallows and along pond or river banks (Larimore 1957). They are sight feeders and use a very simple process of hiding and waiting for food to dart by, and then they ambush their prey. When the warmouth swiftly opens its large mouth, suction is created aiding in the capture of its prey (Larimore 1957). Warmouth rarely eat motionless food and will often spend minutes determining the acceptability of potential food before attacking it (Larimore 1957).

Learning Behavior—In a laboratory setting, the warmouth continued its independent behavior even when learning. The secluded warmouth learned as quickly as the bluegill and more quickly than the largemouth bass which worm was free as compared to which worm was on a hook (Witt 1949). When warmouth were placed in groups, it made more errors with the worms than either the largemouth bass or the bluegill. Warmouth however were the slowest learners of all the sunfish when presented artificial lures (Witt 1949).

Aggressive communication—The warmouth typically has a quiet temperament and exhibits no aggressiveness toward other fish except during nesting (Larimore 1957). When an intruder nears the nest, male warmouth will puff out their opercles or gill plates to appear larger; during this time, the intensity of his red eyes increase and his body turns a light golden color. As the intruder nears, the warmouth will abruptly turn either up or to one side and will push small pulses of water at the intruder with its tail (Larimore 1957). If this fails the warmouth will attempt to nip the intruder. This nest-defending behavior is the same aggressive attitude the male uses in courtship (Larimore 1957).

Genetics[+] Expand

The warmouth was the lone species of the genus Chaenobryttus until recently when it was determined the warmouth was "structurally" similar to and was capable of hybridizing with fish of the genus Lepomis in the Centrarchid family (Becker 1983; Avis et al. 1977). The warmouth is now regarded as a member of Lepomis. Warmouth have 24 pairs of chromosomes, with sex chromosomes not likely to be differentiated from their autosomes (Childers 1968). The male warmouth is thought to be the heterogametic sex with allele expression unencumbered (Childers 1985; Whitt el al. 1975). Hybridization is common between the warmouth and L. cyanellus (greensunfish) and L. macrochirus (bluegill); these hybrids are only "partially fertile" (Childers 1968: Avis et al. 1977). The warmouth along with three other species of the genus Lepomis were found to have "unique hemoglobin patterns in vertical starch gel electrophoresis" (Childers 1968). When hybridization occurred, the blood of bluegill/warmouth, greenfish/warmouth and the warmouth/greenfish F1 hybrids, was found to have even greater gas transport attributes than their parents thus creating "hybrid vigor" (Childers 1968). Hybridization with other Lepomis within its habitat does not appear to be affecting the species health or survivability.

Conservation[+] Expand

Distribution of warmouth is prevalent throughout the south and southeastern United States. Warmouth are secure in Texas, Louisiana, Mississippi, Alabama, Oklahoma, Tennessee, North Carolina, Virginia and Michigan. Populations in Arkansas, Georgia, Kansas, Kentucky, Indiana, Ohio and Wisconsin are considered apparently secure. Populations in Pennsylvania and Illinois are vulnerable. West Virginia populations are imperiled. Populations in Ontario Canada are critically imperiled.

Acknowledgements[+] Expand

There is no information on the subject at this time

Remarks[+] Expand

Economic aspect—The economic importance of the warmouth comes from their popularity as food and as a small sport fish, especially for the cane-pole fisherman (Larimore 1957). The warmouth is an enjoyable species to catch as they have an aggressively hard strike, often breaking the surface of the water. They are accessible with or without a boat, as they are easily found in shallow water around trees, stumps and vegetation. They can be an excellent food fish depending on the quality of their habitat and the accessibility of food.
Food fish—Warmouth are excellent food fish if caught from a clean habitat with a plentiful supply of prey. They have a similar taste and texture between a bluegill and a largemouth bass (Larimore 1957). They can sometimes be small and bony and have a muddy flavor. This is why habitat and a readily available supply of food are vital. Anglers often value the warmouth for their gamy flavor and plump size (Larimore 1957).
Sport fish—Warmouth can be a highly prized sport fish because it can be caught on a light rod or pole and with artificial or live bait. Cane-pole fishermen have success with earthworms, minnows, crickets, grasshoppers, grubs or just about any type of insect, hooked underneath a pole float. Small artificial lures also work well on light rods, and warmouth have a particular "gullibility" for artificial lures which makes it an attractive small-sport fish (Witt 1949). Warmouth are also caught using a fly rod, especially in the spring (Becker 1983).
Because of its size, the warmouth is not considered a first rank sport fish, but the aggressiveness the species use to attack its bait makes for an entertaining angling experience. Easy access to warmouths' shallow-water habitat provides everyone the opportunity to fish. The two pounders will provide an excellent meal.
Lepomis gulosus as a laboratory fish—Warmouth are good laboratory fish as they transport well, are small enough for aquariums and large enough for handling. They tolerate low dissolved oxygen levels, are a good biological assay species, have a quiet disposition, and feed on a variety of, preferably live, food (Larimore 1957). Warmouth also have a relatively long spawning season which allows for a variety of specimen sizes available throughout the laboratory year. The warmouth have different individual and group learning behaviors from other species within the Centrarchidae family (Larimore 1957). Most of all, they will nest and spawn in a laboratory environment without being distressed by observers (Larimore 1957) and typically live six to seven years (Mettee 1996).
The Lepomis gulosus artist—One painting detailing all of the warmouth's subtle differences kept reoccurring throughout the warmouth research (Figure 1). Visual characteristics were easily understood through the drawings of Duane Raver, who spent thirty years working for the North Carolina Wildlife Resources Commission after graduating with a Fishery Management degree from Iowa State in 1949 (Farlow 2009). Currently at 86, he continues to draw and paint after years of studying his subjects. I have been in contact with him through the United States Postal Service.

Literature Cited[+] Expand

Avise, J.C., D.O. Straney, and M.H. Smith. 1977. Biochemical genetics of sunfish IV relationships of Centrarchid genera. Copeia 2:250–258.

Becker, G.C. 1983. Sunfish family–Centrarchidae. Pp. 817–821 in Fishes of Wisconsin. University of Madison Press, Madison.

Berra, T. M. 2008. Centrarchidae sunfishes. Pp. 391–398 in Freshwater fish distribution. University of Chicago Press, Chicago.

Carter, R. G. and J. D. Williams. 2002. Pp. 345 in National Audubon Society field guide to fishes: North America. Alfred A. Knoph, New York.

Childers, W. F. 1968. Hybridization of fishes in North America (family Centrarchidae). Illinois Natural History Survey Bulletin., accessed 3 March 2013

Cook, F. 1959. Warmouth. Pp. 179 in Fresh water fishes in Mississippi. Mississippi Fish and Game Commission Press. Jackson.

Etnier, D. A., and W. C. Starnes. 1993. Lepomis gulosus (Cuvier), Warmouth. Pp. 413–415 in The fishes of Tennessee. University of Tennessee Press, Knoxville.

Farlow, Shannon. 2009. Small strokes. Our state North Carolina., accessed 15 March 2013.

[FFWCC] Florida Fish and Wildlife Conservation Commission. 2013. Warmouth., accessed 12 March 2013.

Hay, O. P. 1894. Lampreys and fishes of Indiana. Pp. 153 in Indiana Department of Geology and Natural Resources, Nineteenth Annual Report. William B. Burford Printing, Zionsville.

Hubbs, C. L., R. J. Edwards, and G.P. Garrett. 1991. An annotated checklist of freshwater fishes of Texas, with key to identification of species. Texas Journal of Science, Supplement 43(4):1-–6.

Hunt, B.P. 1960. Digestion rate and food consumption of Florida gar, warmouth, and largemouth bass. Transactions of the American Fisheries Society 89(2):206–211.

Laerm, J. and B.J. Freeman. 1986. Warmouth. p. 90–91 in Fishes of the Okenfenokee Swamp. University of Georgia Press, Athens.

Larimore, R.W. 1957. Ecological life history of the warmouth Centrarchidae. Illinois Natural History Survey, Bulletin 27(1):):1–83.

McMahon, T. W., G. Gebhart, O. W. Maughan, and P. C. Nelson. 1984. Habitat suitability index models and instream flow suitability curves: warmouth. U.S. Fish and Wildlife Survey FWS-–BS/82:10.67 1–18.

Mettee, M. F., P. E. O'Neil, and J. M. Pierson. 1996. Warmouth. P. 535 in Fishes of Alabama and the Mobile Basin. Oxmoor House Inc. Birmingham.

Moyle, P. B. 1976. Sunfish family, Centrarchidae. Pp. 307–308 in Inland fishes of California. University of California Press, Berkeley.

O'Connell, M. and J. V. Vrancken. 2010. Effects of Hurricane Katrina on freshwater fish assemblages in a small coastal tributary of Lake Pontchartrain, Louisiana. American Fisheries Society, 139:1723-–1732.

[ODNR] Ohio Department of Natural Resources. 2013. Riverine fish., accessed 26 February 2013.

Page, L.M. and B.M. Burr, 1991. A field guide to freshwater fishes of North America north of Mexico. Houghton Mifflin Company, Boston.

Pflieger, W. L. 1975. The fishes of Missouri. Warmouth: Leopmis gulosus. The Missouri department of conservation.

Robins, C.R., R.M. Bailey, C.E. Bond, J.R. Brooker, E.A. Lachner, R.N. Lea and W.B. Scott. 1991. Common and scientific names of fishes from the United States and Canada. American Fisheries Society Special Publication (20):183.

Ross, S. T. and W. M. Brenneman. 2001. Lepomis gulosus (Cuvier), warmouth. Pp. 412–414 in The inland fishes of Mississippi. University Press of Mississippi, Jackson.

[TPWD] Texas Parks and Wildlife Department. 2004. Warmouth (Leomis gulosus)., accessed 10, March.

[USFWS] United States Fish and Wildlife Service. 2010. Duane Raver freshwater fish ar collection on CD., accessed 12 February 20133.

[UWSGI] University of Wisconsin Sea Grant Institute. 2013. Warmouth body., accessed 21 February 2013.

Wallus, R. and T. P. Simon (eds). 2008. Spawning act. Pp. 142–143 in Reproductive biology and early life history of fishes in the Ohio River drainage. CRC Press, Boca Raton, Florida.

Witt, A. 1949. Experiments in learning of fishes with shocking and hooking as penalties. Pp. 1-–60 in Master's thesis. University of Illinois, Urbana.

Contributing editor of this account was Clinton Smith.

Order[+] Expand

Perciformes, also called the Percomorphi or Acanthopteri, are the largest order of vertebrates, containing about 40% of all bony fish. Perciformes means "perch-like". They belong to the class of ray-finned fish, and comprise over 10,000 species found in almost all aquatic environments. The order contains about 160 families, which is the most of any order within the vertebrates.[1] It is also the most variably sized order of vertebrates, ranging from the 7–mm (1/4–in) Schindleria brevipinguis to the marlins in the Makaira species and the heaviest of bony fish, Mola mola. They first appeared and diversified in the Late Cretaceous. Among the well-known members of this group are cichlids, California sheephead, sunfish/bluegills, damselfish, bass, and perch.

Family[+] Expand

The sunfish are a family (Centrarchidae) of freshwater ray–finned fish belonging to the order Perciformes. The type genus is Centrarchus (consisting solely of the flier, C. macropterus). 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.

About This Project.

This website is an ongoing project by Ichthyology students of the Department of Wildlife, Fisheries, and Aquaculture, within the College of Forest Resources to provide information on the biology and ecology of fishes that occur in Mississippi. These accounts were written by undergraduate students as a course assignment, generally follow the format of Mammalian Species, and nomenclature follows Nelson 1994.

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