SRAC Publication No. 723

VI June 2000 PR

Species Profile

Conrad W. Kleinholz1

Bigmouth buffalo are a popular backwaters or oxbows in foodfish and support a large rivers, often in flooded or veg- commercial fishery throughout etated areas. Bigmouth buffalo the lower val- are also common in large ley. Most “cultured” buffalo are reservoirs throughout the caught by commercial fisher- Mississippi River drainage. men and held in ponds until Their range extends from harvested and sold. Producing and buffalo in ponds may in Canada, and from Montana now be economically feasible, to Ohio, south to and because market demand is west to . The bigmouth increasing while commercial mostly eats , but harvest is declining. Several also benthic larvae, live haulers transport buffalo and detritus. from the Mississippi and Buffalo are excellent polyculture Cladocerans and copepods are the Arkansas Rivers to markets in candidates. By harvesting plank- preferred zooplankton forage, and Chicago, New York, Seattle, ton and detritus, bigmouth buffa- small zooplankters are eaten more Toronto and Montreal, and more lo can maximize feed efficiency in often than large prey such as of their customers are requesting intensively managed culture adult calanoid copepods. cultured fish. The reported 1998 ponds. Disadvantages include the There are three of buffalo, harvest of buffalo was 22 million difficulty of sorting them at har- but only the bigmouth eats plank- pounds, and 94 percent of the har- vest and the increased labor ton. Producers should be able to vest was by gill nets and trammel required in processing a scaled identify and avoid smallmouth nets. Eighty-three percent of the fish. and , which do not 1998 harvest was sold to African- perform as well as bigmouth buf- Americans. Six percent of the har- Life history and falo. All three species are common vest was from seining or culture to the Mississippi River drainage and was sold to Asians or central environmental requirements system and occur in both rivers Europeans. The growing market and reservoirs. for buffalo may indicate increased The bigmouth buffalo, per capita consumption or the fact The , I. cyprinellus, has a maximum size of that in the last decade the Asian bubalus, has a small, ventral about 80 pounds (36 kg). It has a population in the U.S. has grown mouth. Its predominant diet is terminal, oblique mouth with thin more than 125 percent and the benthic macroinvertebrates and lips. There are more than 60 gill African-American population 13 some plant material. Smallmouth rakers (average of 72) on the first percent. buffalo are most often found in gill arch, and a single row of deep, clear pools in river systems. weakly developed pharyngeal The maximum recorded size is 15 teeth. Bigmouth buffalo occur 1 pounds (13.5 kg). Langston University, Langston, most frequently in slow-moving . The black buffalo, I. niger, also As the ponds are filled, add lime are observed along the shoreline. prefers riverine habitats and its (if necessary) to obtain an alkalini- If broodfish are not removed, they diet is similar to that of the small- ty above 50 ppm, and fertilize will compete directly with fry and mouth buffalo. Black buffalo have with 10 to 15 pounds per acre (13 fingerlings for zooplankton for- a ventral, slightly oblique mouth to 17 kg/ha) of 18-46-0 or similar age. with thick, fleshy lips. The black inorganic fertilizer. If surface buffalo is found in steeper gradi- water is used to fill the pond, it Hatchery production ent streams than either small- should be filtered through 125- Select broodstock and move them mouth or bigmouth buffalo. micrometer screening to eliminate to holding facilities in the hatch- Maximum weight of black buffalo predaceous zooplankton. - ery. Sperm should flow freely is about 35 pounds (16 kg). ing ponds should contain water from males when the abdomen is only a short time (usually 2 to 3 gently squeezed. Separate the days) before spawning to reduce Spawning techniques sexes in the holding facilities to insect predators and maximize control spawning. Inject females There are two types of reproduc- zooplankton production. See with pituitary (4 to 8 mg/kg) tion—traditional pond spawning SRAC publication 700, “Zoo- or a mixture of pituitary and HCG and hatchery production. Pond plankton Succession and Larval (Human Chorionic Gonadotropin, spawning is easy and requires no Fish Culture in Freshwater 2.5 to 5.0 mg/kg + 60 to 750 hatchery facilities, but the number Ponds,” for details. Stock brood- IU/kg, respectively) to induce of fry is unknown until finger- fish in the spawning pond while it final maturation, as mentioned in lings are sampled or sorted for is filling. Stock 15 to 18 fish per SRAC publication 425, “Hormone restocking in growout ponds. acre (37 to 44/ha), with a ratio of Preparation, Dosage Calculation, Hatchery production requires two males per female. Broodfish and Injection Techniques.” One more facilities, but fry production should be at least 2 years old and formulation of HCG is now can be carefully controlled. When weigh more than 3 pounds (1.4 approved for use with all finfish, fish numbers are known rather kg). The sexes are readily distin- but must be obtained by prescrip- than estimated, ponds can be guished because males develop tion from a veterinarian. The managed so the resulting finger- breeding tubercles over most of injections are given in two lings are the desired size for the body surface and usually pro- doses—an initial dose of 10 to 33 growout during the next season. duce milt when the abdomen is percent of the total, and a final Broodfish can be maintained with gently squeezed. Females have no injection within 6 to 8 hours. other fish during most of the year, tubercles; they have thicker bodies Buffalo will usually ripen within rather than kept in a separate than males and an enlarged, usu- 24 to 36 hours of the initial injec- brood pond. The broodfish will ally inflamed, vent during pres- tion. Dry strip the adults and fer- do very well in a polyculture pawning and reproductive peri- tilize the eggs in a plastic tub, pond at rates up to 200 per acre ods. Egg production is approxi- then add water to the tub and (500/ha), and will probably need mately 100,000 per pound allow eggs to harden for 2 hours. no supplemental feeding. If buffa- (250,000/kg) of body weight. Maintain at least 4 mg/L dis- lo broodfish are kept in a separate Eggs are approximately 1/16 inch solved oxygen in the water during pond, plankton populations can (1.5 mm) in diameter. Buffalo are hardening. After hardening, sepa- be maintained at desired levels by group spawners; the adhesive, rate the eggs by simply rolling occasional fertilization with inor- sinking eggs are scattered among them gently between the fingers. ganic fertilizers or low quality, flooded vegetation in water 1.5 to Then incubate them in hatching rotting hay. Broodfish also can be 4 feet (0.5 to 1.2 m) deep. Water jars. Other methods of separating fed slow-sink catfish pellets at 1 depth at spawning should be 3 to the eggs begin 1 to 5 minutes after to 2 percent of their body weight. 6 feet (0.9 to 1.8 m). the eggs are fertilized. One Pond spawning Adults can be induced to spawn method uses a saturated suspen- by quickly increasing water level sion of Fuller’s Earth, commonly Bigmouth buffalo spawn at water in a brood pond. If there is no sold as cat litter. Be sure to use a o temperatures of 65 to 75 F (18 to vegetation in the pond, add brand without additives or per- o 24 C). Pond spawning is most spawning mats or scatter a coarse fumes. Combine 2 to 4 parts by successful if spawning/nursery hay, such as Johnson grass, at the volume of the suspension per ponds are prepared ahead of edge of the pond. Coarse hay does part of eggs. Aerate the mixture time. Annual rye, wheat or rice not decay as quickly as grass hay with an airstone, and replace the can be planted during the winter or wheat or rice straw, so it does suspension every 10 minutes on the interior levees and bottoms not reduce the dissolved oxygen until the eggs are no longer sticky of dry ponds. The plants will in the vicinity of developing (probably at least 20 minutes). serve as spawning substrate and embryos or newly hatched fry. Then flush the suspension and green fertilizer when the ponds Fertilize the brood pond with hatch the eggs in hatching jars. are filled. Small ponds (0.1 to 1.0 inorganic fertilizer as for spawn- The Fuller’s Earth method is most acre; 0.04 to 0.4 ha) are easier to ing ponds. Move broodfish to effective when the total alkalinity manage than production ponds. another pond when schools of fry is less than 250 ppm. Other methods use salt and urea, fol- (100-mm) fingerlings during the essary. Harvest can be difficult in lowed by tannic acid, or tannic first season. Fry stocked at 5,000 polyculture systems, where there acid alone. For details, refer to per acre (12,000/ha) should grow are many sizes, species and SRAC publication 426, to 7- to 8-inch (175- to 200-mm) behaviors of fish. If harvest is “Techniques for Taking and fingerlings. done with catfish seines, do not Fertilizing the Spawn of Fish.” begin to sort the fish immediately Eggs hatch within 5 days at 65o F Pond production after seining. Instead, give the fish (18.5o C), and within 3 days at 75o of foodfish sufficient room to move, as when F (24o C). Transfer fry to fertilized the seine is positioned to allow nursery ponds as soon as they Buffalo fingerlings are easily small catfish to escape the mesh, become free-swimming. stressed during handling. They and the buffalo will orient them- are easily bruised, and lose scales selves at the edge of the fish mass Hatching and fry rearing when handled with knotted mesh near the upper margins of the netting. Injuries sustained during seine. There, they can be removed Fry begin feeding on small zoo- handling increase the incidence of easily by hand if the farm is small. plankton 3 to 5 days after hatch- diseases. Fingerlings should be On large farms, the buffalo should ing. A good bloom of rotifers, moved in water when possible, be seined with a large mesh seine copepod nauplii, and early instars and handled only in small num- so that only a fraction of the total of cladocerans is necessary for bers when out of water. Age 0 fin- fish biomass is caught. For live- first feeding and growth of fry. gerlings also can be polycultured haul markets, buffalo should be Consult SRAC publication 700, with other species, but may handled in loading baskets made “Zooplankton Succession and increase Lernea (anchor parasite) with knotless mesh. Loading rates Larval Fish Culture in Freshwater infestations in other soft-bodied, for livehaul markets are about the Ponds,” for details on zooplank- scaled fish such as goldfish, fat- same as for channel catfish. Severe ton succession, and SRAC publi- head minnows and golden shin- hemorrhage and scale loss will cation 469, “Fertilization for Fish ers. Age I fingerlings can be occur if buffalo are handled with Fry Ponds,” for pond fertilization stocked at 100 to 250 fish per acre knotted mesh nets. This will details and schedules. A zoo- (250 per 620/ha) in polyculture reduce their appearance and mar- plankton bloom with appropriate ponds for growout to market size ket value. Fish damaged during sizes of zooplankton (0.05 to 0.1 of 2 to 5.5 pounds (1 to 2.5 kg) harvest should be processed, usu- mm) should be present for the during the second year, with no ally as gutted, fresh fish. fry’s first feeding. If fry were pro- effect on catfish food conversion. duced in a hatchery, the nursery Take care to harvest market-sized Diseases pond should be filled and fertil- fish annually. Buffalo will spawn, ized about 5 days before stocking even with no apparent substrate, Fingerling buffalo are particularly fry. Schools of fry should be if they are allowed to remain in susceptible to anchor parasites, observed swimming along the the polyculture ponds beyond Lernea cyprinacae, but most buffalo shoreline within 7 to 10 days after year 2. It is possible that excessive are Lernea-free after they reach hatching. Fry 0.25 to 0.5 inch (6.5 populations of buffalo could occur 12 inches (30 mm). The female to13 mm) long are particularly if adults are not harvested. In cat- parasite has holdfasts that attach prone to starvation if ponds are fish ponds, fingerling buffalo to the fish between scale margins, improperly fertilized. Check zoo- could serve as supplemental for- at fin insertions, and at the edges plankton density daily and fertil- age, but forage fish may con- of the . The parasite is ize as necessary. Adding small tribute to off-flavor in catfish. visible as a fine, wire-like protru- amounts of fertilizer frequently is Buffalo have water quality sion from 1/16 to 1/2 inch (1.5 to more beneficial than adding large requirements similar to channel 13 mm) long, often with a pair amounts infrequently. Zooplank- catfish. Bigmouth buffalo also of pale green egg sacs 1/4 inch ton blooms can be maintained by readily take sinking fish food, but (6 mm) long. There is usually an fertilizing with granular18-46-0, have not been observed feeding at inflamed, swollen lesion at the liquid 11-37-0, or similar inorganic the surface on floating feeds. attachment site. Secondary infec- fertilizers. Organic fertilizers such tions of the protozooan Epistylis as composted manure, alfalfa or Harvest or the bacteria Flavobacterium soybean meal may be added as columnare are common with severe well. Supplement pond fertiliza- Fingerlings or foodfish weighing anchorworm infections. Both tion schedules with sinking feed less than 2 pounds (1 kg) should appear as fuzzy, often brown within 30 days to maintain good be handled with knotless mesh growths near the anchorworm fish growth. Sinking feed should nets, if possible. Add 1 percent site. Secondary infections can be be added at approximately 1 per- salt to the hauling water, maintain legally treated only with formalin- cent of the estimated weight of the dissolved oxygen near saturation F®. There is no currently fingerlings per day. Reduce stock- in the seining area and in the approved therapeutant for treat- ing densities to 25,000 per acre hauling tank, and keep fish in the ment of Lernea infestations on (62,000/ha) to obtain 4-inch hauling tank no longer than nec- food fish. The best treatment is to stock at moderate rates and main- smaller markets do exist, or can for fingerling production included tain good water quality. Maintain be developed, throughout the U.S. both carp pituitary and HCG ($10 a bloom adequate for good pro- for both live and processed fish. per acre; $25/ha). The costs also duction of zooplankton, but not There is some market for selling included 150 pounds per acre dense enough to deplete dissolved fingerlings to other culturists. (370.5 kg/ha) of sinking feed ($38 oxygen. Infestation is aggravated per acre, $94/ha), and 50 pounds by crowding and poor water qual- Economics of buffalo per acre (56 kg/ha) of 18-46-0 fer- ity. production tilizer. Harvesting fingerlings cost $15 per acre ($37/ha). Marketing Buffalo monoculture is not recom- Assumptions for foodfish produc- mended. The capital investment tion included a pond stocked with Buffalo marketing is currently associated with pond construction hampered by large, seasonal vari- 5,000 catfish and 200 buffalo per would probably not be recovered acre (12,000 catfish and 500 buffa- ations in availability and product unless the fish were sold retail. quality. These constraints are simi- lo/ha). An additional seine haul However, when used as a polycul- (with a large mesh seine) beyond lar to those encountered in the ture fish, the overhead is drastical- early catfish industry when much that necessary for harvesting cat- ly reduced except for labor need- fish was included ($15 per acre; of the supply was wild-caught. ed during harvest. Buffalo are Buffalo are often marketed live, or $37/ha). Harvesting costs would attractive primarily as a crop that increase substantially if a large as fresh, whole dressed fish. They can be produced on food sources have large, forked, intermuscular mesh seine was purchased specifi- (such as uneaten feed and plank- cally for buffalo production. bones in the dorsal musculature ton) that would otherwise be anterior to the vent, which dis- Alternatives include sharing a irrecoverable. Production costs seine with other producers, hav- courages the marketing of fillets. increase with the intensity of the The live fish market is targeted to ing a custom harvester seine the culture method. Harvest and han- buffalo, or seining the buffalo and Asian consumers, who prefer to dling are the biggest expenses. have the fish gutted with scales the catfish together. No extra food Table 1 presents partial budget was added to the pond for the and head left intact. For African- analyses for producing fingerlings American consumers, fish are buffalo. Fish were assumed to be and foodfish in a catfish polycul- sold wholesale ($0.65 per pound; whole dressed. The most common ture pond. dish in restaurants is the fried rib $1.37/kg) at the pond bank; prices section. However, the meat is par- Assumptions for fingerling pro- should be at least doubled for ticularly suited for sale as a duction were 10,000 fish per acre retail sales. These costs and smoked product. While most fish (25,000/ha), reared to 0.1 pound returns do not reflect additional are now sold to live haulers for (45.0 g) and sold for $1.00 per expenses associated with long dis- resale in large metropolitan areas, pound ($2.50/kg). Hatchery costs tance live hauling.

Table 1. Partial budget analysis per surface acre (hectare) of buffalo production. Culture phase Total benefit Total cost Net benefit Fingerlings, 6-8 in. (150-200 mm), 10,000/A $1,000 ($2,500) $78 ($193) $925 ($2,285) (25,000/ha) Foodfish, 200 fish/A (500/ha), $487.50 $15 (37.50) $450 ($1111.50) mean weight 3.75 lbs. (1.7 kg)

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.