SRAC Publication No. 724

VI August 2000 PR

Species Profile Sunfish

Martin W. Brunson1,2 and Joseph E. Morris3

The sunfish family species profile will address only As interest grows in producing (Centrarchidae) includes 30 the culture of the genus Lepomis, these fish for human consump- species, and is found only in commonly called bream, sunfish, tion, producers will need to grow North America. This family sun perch or simply panfish. them to market size and ensure includes the black basses Refer to SRAC Publication 722 for that they have the appearance, (Micropterus spp.), crappies information on largemouth bass. texture and flavor consumers (Pomoxis spp.), and the bream Sunfish have been cultured almost desire. Bluegill and redear, as well (Lepomis spp.), as well as the gen- exclusively to produce fingerlings as several sunfish hybrids, have era Amboplites, Elassoma, for stocking recreational fishing good flavor and texture, low-fat Enneacanthus, Centrarchus, waters. Bluegills and redear sun- flesh, and good storage qualities. Archoplites and Acantharcus. This fish are stocked for forage, and Consumers recognize and accept family is one of the most popular with largemouth bass they also them. In terms of temperature and and widely known gamefish provide excellent sportfishing. water quality requirements, groups in North America. Historically, most state and feder- growth rates, trainability to manu- Anglers like sunfish because of al hatcheries produced large num- factured feeds, and fecundity and their fierce tenacity when caught bers of sunfish and distributed ease of spawning in captivity, all by hook-and-line; their firm, them to the public through vari- lepomids, in general, are easy to white flesh; and their favored sta- ous state and federal fish stocking grow. The bluegill and bluegill tus as “bread and butter fish.” In programs. Now many private hybrids may be easiest to culture addition to their utility as sport hatcheries are specializing in the to adult sizes. The most common and food fish, the lepomid sunfish production of gamefish for stock- hybrid is the male bluegill X species are generally stocked in ing, so public hatcheries and state female green sunfish, which has a impounded waters as forage fish agencies have reduced or elimi- desirably high male:female sex for predators such as bass. Most nated their production of game- ratio in the F1 generation. Other anglers are familiar with these fish for the public. hybrids may also be successful, fish. despite variable sex ratios, if tech- Another production scenario is to Bass, crappie and bream have niques such as ploidy manipula- stock fingerlings at high densities, tion can be perfected. been cultured for the past 50 feed them a manufactured feed, years, primarily to provide finger- and grow them to adult sizes suit- Biology and natural lings for stocking recreational able for marketing as foodfish ponds and lakes, or for use in (225 to 340+g or 0.5 to 0.75+ history research. There is increasing inter- pounds) or gamefish (110 g or 0.25 est in culture of these fish for The centrarchids are perciform pound). These fishes seem to have fish with a spiny dorsal fin (with human consumption and for use potential for both food fish and in fee-fishing operations. This 6 to 13 spines) followed by a soft fee-fishing markets. The culture of dorsal fin. The anal fin has at least hybrids has been studied more three spiny rays at its origin, fol- 1 Mississippi State University than the culture of pure species, lowed by numerous soft rays. The 2 Correspondence author but consumer interest will likely pelvic fins are located immediate- 3 Iowa State University stimulate additional research. ly beneath the pectoral fins and contain one spine and five soft Warmouth for species recognition, but will rays. The caudal fin has 17 princi- hybridize readily if unable to The warmouth, also called “gog- pal rays. Proper identification is locate a mate of the same species. gle-eye,” inhabits sluggish waters, critical to successful production, Thus, proper identification of both preferring weeds or debris such as because the genus Lepomis readily sexes is vital to successfully pro- logs, stumps and brush piles. This hybridizes. ducing the desired offspring. species has not been widely Bluegill and green sunfish males There are eleven species in the stocked in recreational waters, but in breeding condition are easily genus Lepomis, but only the is popular with anglers where it is distinguished from females, but bluegill (L. macrochirus), redear abundant. Its primary importance redears and warmouth sexes are sunfish (L. microlophus), war- to aquaculture has been in the more difficult to differentiate. mouth (L. gulosus), and green production of hybrids with the Experienced culturists can usually sunfish (L. cyanellus) and their other primary species. It has a distinguish males from females on various hybrids have been widely dark, olivaceous to brown body, the basis of external characteristics cultured as sportfish. Although with dark splotches on the sides such as color, body shape or size, other lepomids may have culture and the fins. The cheeks and oper- and distention of the abdomen and market potential, these four cula have three to four dark bars caused by enlarged ovaries or the have been the focus of research. radiating posteriorly from the eye, size and shape of the urogenital and the eye is often reddish. The sinus. Bluegill mouth is larger than that of the bluegill and the redear, and the It is easy to express eggs or milt The bluegill may be the most well from ripe broodstock. However, known of all the sunfish, and it is body is not as laterally com- pressed as in these species. broodstock often are not ripe at certainly the most popular with the time of stocking and identifi- anglers and consumers. Green Sunfish cation. A simple method of prob- Originally distributed from the ing for eggs involves using a 2- to Great Lakes south to the Gulf of The green sunfish may be one of 4-inch (5- to 10-cm) long capillary Mexico, it has been stocked the most adaptable, abundant and tube that is 0.04 to 0.05 inch (1.1 to throughout North America as a environmentally tolerant of the 1.2 mm) in diameter. The tube is gamefish. It is equally at home in sunfishes. It is found in a wide inserted into the urogenital sinus, lakes or streams, but is most variety of habitats ranging from then angled slightly back toward abundant in shallow, eutrophic ponds and lakes to river systems. the tail and slightly to one side. lakes and ponds. The bluegill is This hardiness makes it of interest With the application of light pres- identified by its deep, laterally as a “bait” fish, especially for set- sure, the tube passes through the compressed head and body and lines or trot-lines for catfish. In oviduct into the ovary. A finger is small mouth. The opercular flap some states, however, this fish is then placed on the open end of is black, and individuals longer classified as a game fish, and thus the tube to seal it before it is than 2 inches (51 mm) have a cannot be sold for this purpose. removed for inspection. If no eggs dark blotch at the posterior base Characteristic colors of the green are retrieved, the fish should be of the dorsal fin. The sides usual- sunfish include a blue-green to rejected as a brood fish. This is a ly have eight to ten sets of double dusky dorsum and sides, with a simple procedure, but must be vertical bars that are chain-like in yellow to white belly. A dark basal done with care to avoid damaging appearance. Body colors range spot is usually present on the pos- the fish. from olivaceous to purple, with a terior base of the dorsal fin. All white to orange belly. fins are yellow to orange tinted, Handling can be stressful to the with occasional bright orange fish and should be done with care. Redear areas and white margins. The Broodstock should be handled in cool water, which is conveniently The redear, like the bluegill, has green sunfish is the species used most often to produce hybrids available during stocking season been widely introduced through- (late winter to early spring). Fish out much of the U.S. and North with either the bluegill or the redear sunfish. should be handled as little as pos- America as a gamefish and a sible, sedated when practical, and companion to the bluegill in man- Culture techniques transported in well oxygenated aged systems. Its common names tanks. Thermal shock should be are “shellcracker” and “chin- avoided at all costs. Refer to quapin.” The redear prefers slug- Broodstock SRAC Publications 390, 392 and gish waters. It is identified by its Broodstock selection is critical in 393 for recommendations on han- olive-yellow to straw-yellow dling and transporting fish. body with gray or dusky spots. the production of sunfish and The breast is bright yellow to their hybrids. Improper identifica- Ideally, sexes should be kept sepa- orange, and the opercular flap is tion of the brood fish can lead to rate until they are stocked into short with a distinct scarlet out- contaminated stocks of offspring, spawning ponds. This allows side margin or spot. because these fish readily broodstock to be sexed in advance hybridize. Sunfish rely upon visu- and held for a period of time in al, auditory and behavioral cues conditioning ponds to prepare them for spawning. It eliminates, ly moves into deeper waters (up species are present, they may prey or at least minimizes, stressful to 6 feet or 2 m) as the water on the fingerlings. Establish a handling, sexing and sorting warms. To build the nest, the male plankton bloom before spawning immediately before the spawning sweeps the caudal peduncle begins, using inorganic or organic season. across a sandy or gravelly sub- fertilizers, or a combination of the Bluegills and redears should be at strate, forming a saucer-like two. For information on fertilizing least 2 years old and 0.25 to 0.5 depression from 2 to 6 inches (50 ponds and establishing and main- pound (110 to 225 g) for maxi- to 160 mm) deep and 4 to 12 inch- taining plankton blooms, see mum productivity, whereas war- es (100 to 300 mm) in diameter. A SRAC Publications 466 and 471. mouth and green sunfish will single colony, often called a “bed,” Once water temperatures reach spawn at much smaller sizes. If may contain as many as 60 nests appropriate levels, spawning will smaller bluegills and redears are and cover several hundred square begin. Warmouth and green sun- used for spawning, they should feet. fish are the first to spawn, with be stocked at higher rates to com- Once nests are constructed, the activity beginning at 70 oF (21 oC). pensate for reduced fecundity and courtship ritual begins. The males Redear spawn when water tem- greater variability of spawn size, (more brightly colored than the perature reaches 75 oF (24 oC), consistency and success. Most cul- females) circle the perimeter of the whereas bluegills do not spawn turists agree that broodstock nest while making a series of until temperature reaches 78 to should be stocked in the winter, grunt-like calls. This behavior 80 oF (26 to 27 oC). All species or at least by early spring, at the attracts the females. A single begin nest building and territorial rate of 20 to 40 pairs per acre (50 female can produce as many as behavior at temperatures several to 100 pairs per hectare). Sex 80,000 eggs, in multiple spawns, degrees cooler than the optimum ratios of broodfish in spawning during a spawning season. A spawning temperature. ponds are typically 1:1. Although female may deposit eggs in more sunfish can obtain much of their than one nest, and more than one Spawning techniques and daily dietary need from organisms female may deposit eggs in a sin- fingerling production in the pond, supplemental feeding gle nest. The males fertilize the may increase fecundity. Feed eggs by releasing milt across the Sunfish can be spawned in the broodstock with a 1/8- to 1/4-inch egg mass, and then aggressively laboratory by manually stripping (3- to 6-mm) floating or sinking defend the nest from invading gametes into petri dishes and then pellet (36% crude protein) as soon predators, periodically fanning mixing milt and eggs with water. as the water temperature reaches the nest to aerate the eggs. Fertilized eggs are placed in clean a level that stimulates feeding Incubation takes 1 to 6 days at petri dishes containing aged tap activity. Feeding rate should be 2 temperatures above 70 oF (21 oC.) water for water hardening, then in to 3 percent of body weight per aerated aquaria. When larvae day. Pond preparation become free-swimming fry, they are transferred to rearing ponds. Sunfish reproductive habits Sunfish can be produced in many Spawning has also been induced types of facilities, and are often in the laboratory or under simu- To produce lepomid fingerlings spawned in laboratory settings for lated field conditions by manipu- for stocking or culture, one must research purposes. Most culture, lating temperature and photoperi- understand the reproductive however, is done in open ponds od. Research to develop improved habits of these sunfishes. Sunfish or cages. In general, spawning spawning and larval rearing tech- are, in general, colonial nest- ponds should be 2 to 5 feet (0.6 to niques continues. builders and multiple spawners. 1.5 m) deep with smooth, uni- In pond spawning systems, Spawning begins in early to mid- formly sloped bottoms to facilitate broodstock are allowed to spawn spring and continues to some the harvest of fingerlings. Ponds freely. One hundred broodfish can degree until early fall, depending should be less than 3 acres (1.2 produce up to 375,000 fry, with an upon the species and the geo- ha), although larger ponds have average of about 100,000 fry per graphic location. Courtship and been used successfully. Ponds acre (247,000/ha). With good nesting behavior are similar for all should have drain pipes so that water quality and optimum tem- lepomids, with slight variations water levels can be controlled, perature, broodfish should pro- by species. and a water source (preferably duce offspring almost immediate- The male typically prepares a nest ground water) for filling the ly. When fry are observed (which in shallow water when the tem- ponds and replacing evaporative should be soon after hatching), perature reaches the preferred losses. Ponds should be filled with begin a feeding program. A fry range for the respective species. well water at least 2 to 4 weeks powder or a mash should be The depth at which these nests are before spawning begins. Ponds offered at first. As fry grow, the constructed depends upon water should be completely free of other size of the feed can be matched to temperature, which in turn fish species. If other sunfish are the size of the fish. With a feeding depends on the time of year. present there is risk of hybridiza- program, fry should grow as Nesting occurs first in warm shal- tion, depredation and disease much as 1 inch per month. lows in early spring, and gradual- transmission; if other piscivorus Fingerlings should reach stocker Cages tolerated by bluegills at 95 oF size of 2 to 3 inches (51 to 76 mm) o Cage culture of sunfishes has been (35 C) is 0.75 mg/L, but this in 60 to 100 days. practiced where pond culture is species tolerates only 1.40 mg/L at 77 oF (25 oC). Bluegills avoid Grow-out to adult size not feasible. Cage culture has cer- tain advantages. It is more flexible areas where dissolved oxygen concentration is below 3.0 mg/L. Until recently, there has been little because many types of water bod- Bluegill fry are reported to grow research on the grow-out of sun- ies may be used. It is more conve- best at 30 oC. fish fingerlings to food size fish. nient to observe and harvest fish, Now, researchers are beginning to and the initial capital cost is rela- Bluegills are not tolerant of high study the production of adult sun- tively low if a suitable pond ammonia concentrations. fish in ponds, cages and inten- already exists. Sunfish meet the Continuous exposure to as little as sive/recirculating systems more desired criteria for cage culture— 0.006 mg/L unionized ammonia thoroughly. rapid growth, tolerance of crowd- can significantly reduce their ed conditions, good growth in growth. Centrarchids, however, Ponds regional environmental condi- have a high tolerance for nitrite, tions, and potential market value. and benefit from a physiology Stocking rates for hybrid sunfish Cage culture requires larger fin- that prevents nitrite from entering in grow-out ponds have ranged gerlings than pond culture, and the blood through the gills. from 1,000 to 10,000 fingerlings they should be graded to ensure per acre (2,471 to 24,710 /ha), but uniform initial size. It is recom- Diseases research in both the Southern mended that 4-inch fingerlings Sunfish are hardy in the wild, but Regional Aquaculture Center be stocked into cages at the rate when stocked into high density (SRAC) and the North Central of six to eight fish per cubic foot culture conditions they can be Regional Aquaculture Center (212 to 282 fish/m3) of cage susceptible to several bacterial (NCRAC) indicates that the opti- volume. mum stocking rate may be 5,000 and parasitic diseases. Columnaris to 7,000 fish per surface acre Sunfish cultured in cages must be is a common bacterial infection in (12,355 to 17,297/ha). Hybrids can fed a complete diet, because there centrarchids, especially when fish be grown to market size of 1/2 to is little or no natural food. A are stressed. External fungus 3/4 pound (230 to 340 g) in 18 to crude protein level of at least 40 (Saprolegnia spp.) can cause signif- 30 months, depending upon percent is recommended. icant mortalities. Parasites such as stocking density, feeding prac- black grub (Uvulifer ambloplitis), tices, and water temperatures. Recirculating systems white grub (Posthodiplostomum Yields have ranged from 750 to Recirculating tank systems may be minimum), and yellow grub 1,700 pounds per acre (837 to a good alternative where land and (Clinostomum marginatum) are 1,926 kg/ha), depending upon the water resources are not adequate common in sunfish. Although size at stocking and the initial to support either pond or cage these parasites usually pose no stocking density. culture. Stocking rates and pro- significant threat to the fish, they can affect appearance and mar- Definite nutritional requirements duction techniques have not been ketability. have not been determined, but the documented, but it is relatively protein requirement of sunfish certain that the higher fixed costs probably lies somewhere between and management inputs associat- Harvest that of rainbow trout and channel ed with tank systems would result Harvesting small (less than 1-inch, catfish. The dietary phosphorus in higher production costs. Like 25-mm) sunfish is stressful to the requirement of one green sunfish cage culture, recirculating systems fish, so most producers do not X bluegill (GS X BG) hybrid is 0.5 will require a nutritionally com- attempt harvest until the fish percent or less of the dry diet. plete, high protein feed. reach an average of 2 inches (50 Both the bluegill and the GS X BG mm). This is the most commonly hybrids grow best when fed diets Water quality requirements stocked size for bluegills, redears containing at least 10 percent The water quality requirements of and sunfish hybrids. Transporting dietary lipid in the form of fish sunfish vary with life stages and fingerlings for stocking is usually oil. Research in recirculating sys- by species. Generally, eggs are delayed until the fall months tems and in ponds suggests that more sensitive than fingerlings or when low water temperatures when natural food is not available adults. For example, bluegill eggs help minimize stress in handling (as in tanks, raceways or cages), tolerate salinities up to 5 percent and shipping. Fall is also the rec- optimum crude protein levels of seawater, but fingerling toler- ommended time for stocking sun- may be at least 40 percent. ance is as high as 30 percent of fish into small impoundments for However, when fish are cultured seawater. recreational fishing. in open ponds where natural food is available, crude protein require- Oxygen requirements are related Pond harvest is usually done by to temperature. For example, the seining. A square mesh seine with ments for formulated feeds are 35 1 to 40 percent. minimum dissolved oxygen level /3-inch (8-mm) mesh will retain sunfish 1.5 inches (37 mm) and the same is likely true for fee-fish- game fish might result in larger, while a mesh size of 1/2 ing markets. Anecdotal evidence increased poaching, the depletion inch (12 mm) will retain sunfish indicates a potential food fish of native fish stocks in streams 2 inches (50 mm) and longer. market, but the breadth and long- and reservoirs, and severe or Harvest from cages and recirculat- term stability of that market are irreparable damage to our recre- ing systems is easier and more not known. For example, in the ational fisheries resources. In at convenient than from ponds, but NCRAC survey, midwestern bro- least three states, illegally harvest- large batch harvests are not as kers, wholesalers, retailers and ed native game fish have, in fact, practical as in ponds, where larger restaurants listed bluegill as one found their way into the legal numbers of fish can be corralled of the top three species they supply of cultured fish. It is with a seine. would like to purchase for their hoped that research will develop a customers. In some states where way of quickly and easily distin- Marketing and economics the marketing of game fish for guishing cultured fish from wild human consumption is illegal, game fish. For now, it is critical A recent survey conducted by the there seems to be a significant that producers consult the wildlife NCRAC estimates that there are black market for sunfish captured and fisheries agencies and depart- 485 producers of sunfish in the from the wild by commercial ments of agriculture in their states U.S., most of them in the southern poachers. This would indicate to determine the legality of cultur- and north central regions (primar- some level of demand, but other ing, processing, transporting and ily Texas and Wisconsin). Bluegill than law enforcement efforts to marketing game fish. Also know is the most commonly produced stem illegal wild fish harvest, no the laws in each state through species (45 percent of north cen- attempt has been made to docu- which you plan to transport fish. tral region producers), followed ment or describe the economics In some cases, simply crossing a by various hybrids (26 percent of and extent of that market. state line with game fish is a vio- producers nationally) and redear lation of the law. (14 percent of producers). Limitations and Research is needed in nearly There are two primary markets. constraints every area of sunfish culture— Approximately 74 percent of pro- defining efficient and economical ducers produce sunfish for sport The two main limitations to fur- production techniques and identi- fish, and about 20 percent supply ther development of a sunfish fying and quantifying markets them to fee-fishing operations. aquaculture industry are legal and marketing strategies. Other production is split among issues and lack of research. The Specifically, more information is food fish, bait fish, and supplying legal issues revolve around the needed on the costs of production fish for scientific research. “game fish” status of the sunfish at every life phase, larval and fry in many states, and the prohibi- There is no reliable economic data nutrition, alternative and more tion on the sale of game fish for on the market for sunfish or the intensive methods of grow-out, human consumption in some of cost of production. Demand for processing, product form, packag- those states. Many fear that the sport fish has increased in recent ing, and consumer priorities. liberalization of the game fish years, and is expected to continue; laws to allow the sale of farmed The work reported in this publication was supported in part by the Southern Regional Aquaculture Center through Grant No. 94-38500-0045 from the United States Department of Agriculture, Cooperative States Research, Education, and Extension Service.