HANDBOOK ON THE ARTIFICIAL REPRODUCTION AND POND REARING .
HANDBOOK ON THE ARTIFICIAL REPRODUCTION ANDPOND REARING OF THE AFRICAN CATFISH CLARIASGARIEPINUS IN SUB-SAHARAN AFRICAA handbookFAO FISHERIES TECHNICAL PAPER 362
iHANDBOOK ON THE ARTIFICIAL REPRODUCTION ANDPOND REARING OF THE AFRICAN CATFISH CLARIASGARIEPINUS IN SUB-SAHARAN AFRICAA HandbookByGertjan DE GRAAF and Johannes JANSSENNEFISCO FOUNDATIONAMSTERDAM, THE NETHERLANDSFAO, FISHERIES TECHNICAL PAPER 362ROME, 1996
iiThe designation employed and the presentation of material inthis document do not imply the expression of any opinionwhatsoever on the part of the United Nations or the Food andAgriculture Organization of the United Nations concerning thelegal or constitutional status concerning the legal orconstitutional status of any country, territory or sea, city or area,or of its authorities, or concerning the delimitation of its frontiersor boundaries.M-44ISBN 92-5-103916
iiiPREPARATION OF THIS DOCUMENTThe African catfish, Clarias gariepinus has been reared foralmost 20 years in Africa with mixed success; the total farmproduction of this species being only 3,978 metric tonnes or7.4% of the total farmed fish production of 69,434 mt in Africain 1994. To a large extent the poor performance of thisfreshwater fish species in Africa has been due to the absenceof reliable production techniques for the reproduction andrearing of the species under practical farming conditionsThe document is based on the practical field experience ofGertjan de Graaf and Johannes Janssen on the artificialreproduction and rearing of the African catfish within FAOfield projects in the Central African Republic, The Republic ofCongo, Kenya and Nigeria. The manual has been written bythe authors as a practical guide for the reproduction and pondrearing of the African catfish, based on methods which haveproven to be successful and reliable in the fieldThe manual was edited by Dr. A.G.J. Tacon and Ms. M. Pageof the FAO Inland Water Resources and Aquaculture Serviceand produced as part of the ongoing activities of the serviceto help to meet the needs of aquaculture workers of MemberCountries for the development of suitable farming techniquesfor the sustainable expansion of aquaculture productionDistribution; FAO Fisheries Department; FAO RegionalFisheries Officers; FAO Aquaculture Projects; FAORepresentatives; FAO Regional Fishery Commissions;Directors of Fisheries and Aquaculture
ivde Graaf, G.J.; Janssen, J.A.L.Artificial reproduction and pond rearing of the African catfish,Clarias gariepinus in sub-Saharan Africa – A handbookFAO Fisheries Technical Paper. No 362. Rome, FAO. 1996. 73 pABSTRACTThe manual is based on the practical field experience of Gertjan deGraaf and Johannes Janssen on the artificial reproduction andrearing of the African catfish within FAO field projects in theCentral African Republic, The Republic of Congo, Kenya andNigeria. The manual is divided into five major sections dealing with: 1) general biology, including feeding habits and reproduction; 2)artificial reproduction, including induced propagation without andthrough hormone injection; 3) fry nursing in earthen ponds,including pond preparation, fertilization, feeding and management;4) monoculture, including feeding methods; and 5) poly culture withTilapia. In addition, information is provided concerning theeconomics of different fingerling and grow-out farming practices inAfrica, and concerning diseases and hybridisation.
vTABLE OF CONTENTS1.INTRODUCTION . 12.THE AFRICAN CATFISH (CLARIAS GARIEPINUSAND CLARIAS ANGUILLARIS). 52.1.2.2.TAXONOMY . 5NATURAL GEOGRAPHICAL DISTRIBUTION. 63.BIOLOGY. 83.1.3.2.3.3.3.4.3.5.DESCRIPTION OF THE GENUS AND SPECIES . 8HABITAT 11NATURAL FOOD AND FEEDING . 11NATURAL REPRODUCTION . 14OOCYTE DEVELOPMENT. . 174.ARTIFICIAL REPRODUCTION. . 234.1.4.2.4.3.GONADAL DEVELOPMENT IN CAPTIVITY. . 23INDUCED PROPAGATION WITHOUT HORMONE TREATMENT.25SEMI-ARTIFICIAL REPRODUCTION THROUGH HORMONETREATMENT. 254.3.1. Hormone induced reproduction in ponds . 274.3.2. Hormone induced reproduction in happaplaced in a pond. 274.3.3. Hormone induced reproduction in concretetanks with a gravel substrate. . 284.4.ARTIFICIAL REPRODUCTION. 304.4.1. Introduction . 304.4.2. broodstock care and selection of ripebreeders 314.4.3. Hormone injection . 32
4.4.4.eggs4.4.5.5.Maturation processes and stripping of the34Incubation of fertilized eggs. . 39FRY NURSING IN EARTHEN PONDS . 435.1.POND PREPARATION, FERTILIZATION AND FEEDING RATES.435.1.1. Cleaning . 435.1.2. Liming . 445.1.3. Fertilization. 455.1.4. Daily supplementary feeding . 475.2IMPACT OF TADPOLES . 475.3NURSING OF CATFISH LARVAE IN PROTECTED PONDS . 525.3.1. Stocking density of the catfish larvae . 535.3.2. Size and form of the nursing pond . 555.3.3. Duration of the rearing period andcannibalism among the catfish fingerlings. . 575.3.4. Pond monitoring and predator control . 606MONOCULTURE OF AFRICAN CATFISH. 616.16.2STOCKING RATES . 61FEEDING 627.POLY CULTURE OF AFRICAN CATFISH WITH NILETILAPIA738.MISCELLANEOUS. 798.1ECONOMICS. 798.1.1 Economics of fingerling production . 798.1.2Economics of polyculture and monoculture. 838.2DISEASES 888.3HYBRIDIZATION . 899REFERENCES . 92
ANNEX I:FILM.ANOU IS RAISING CATFISH, A TRAINING100
1.INTRODUCTIONPond culture is not a traditional farming practicein most parts of Africa. Introduced after the Second WorldWar there was an initial spectacular development with about300,000 ponds being operational, mainly rearing Tilapia spp,in about 20 African countries by the end of the fifties(Meschkat, 1967). Since then fish culture has not made muchfurther progress and has in many cases even declinedresulting in the abandonment of fish ponds by discouragedfarmers. According to the authors this failure has beenattributed to:*The harvesting of too many small stunted tilapiafrom over populated ponds because of the use of poorhusbandry techniques*The dependency on subsidizedservices and fingerling distribution centres.extension*Misjudgement of the motivation of the rural fishfarmers by policy makers, and the creation of the myth thatthe rural farmer will willingly take up fish farming for foodsecurity or as a source of protein for their family. This is mostlikely not the case, the primary motivation of rural fish farmergenerally being income generation.*Failure to apply adequate resources (which maybe naturally limiting) such as water and feed.By the end of the sixties, a reorientation toincrease aquaculture production was proposed that included;
*A modification of the farming technique forTilapia in which seed production and on-growing tomarketable sized fish are separated and the introduction ofmonosex tilapia culture (Pruginin, 1967 and Shell, 1968).*Identification of new suitable speciesaquaculture were identified (Lemasson and Bard, 1968).forIt was soon recognized that the African catfishClarias gariepinus (Burchell, 1822) was one of the mostsuitable species for aquaculture in Africa (CTFT, 1972;Micha, 1973.; Pham, 1975; Jocque, 1975; Kelleher andVincke, 1976; Richter, 1979.; Hogendoorn, 1979) and sincethe 1970's it has been considered to hold great promise forfish farming in Africa; the African catfish having a high growthrate, being very resistant to handling and stress, and beingvery well appreciated in a wide number of African countries.The development of a reliable method for theproduction of Clarias gariepinus fingerlings was one of thepriorities of aquaculture research in Africa (Anonymous,1987a). Hormone-induced reproduction of the African catfishusing deoxycorticosterone acetate, human chorionicgonadotropin and common carp pituitaries has been carriedout successfully (Hogendoorn and Wieme, 1976; Hogendoornand Vismans, 1980; Micha, 1976; Kelleher and Vincke, 1976;El Bolock, 1976).Hogendoorn (1980) and Hogendoorn andVismans, (1980) successfully developed an intensiveproduction system for African catfish fingerling productionbased on the use of Artemia salina nauplii and a commercialtrout starter as feed. However the existence of technicallyfeasible farming methods and manuals (Viveen et al., 1985)did not guarantee a successful implementation, as the impactof local socio-economic and technical conditions are more
often than not always under-estimated (Anonymous, 1987b).The introduction of intensive rearing methods in the CentralAfrican Republic and the Ivory Coast encountered numeroustechnical and economic problems (Janssen, 1985a, 1985band 1985c; de Graaf, 1989).The main problem of fingerling production withinponds was fish survival rate which was unreliable and varied2between 0 - 60 fingerlings/m /cycle (Micha, 1973, 1976;Hogendoorn, 1979; Hogendoorn and Wieme, 1976; Kelleherand Vincke, 1976). It has been suggested that the lack ofappropriate feed and the presence of predators are likelycauses of mortality. In the late 1980's a simple and reliablemethod was developed in Congo Brazzaville for the nursingof Clarias gariepinus within protected ponds (de Graaf et al.,1995) and this study indicated that competition for feed andcannibalism were the major factors affecting pond nursing ofClarias gariepinus. The methodology as developed in CongoBrazzaville is now being used in many other African countriesand an instruction video on this technique; "Anou is /PRC/88/007, Phase II) in Congo Brazzaville andcan be obtained from FAO Headquarters in Rome or from theNEFISCO-foundation, Amsterdam, the Netherlands (seeAnnex I).The last twenty years has seen considerablegains in our knowledge concerning the reproduction andrearing of Clarias gariepinus, and in particular through theactivities of FAO projects in the Central African Republic, theRepublic of Congo (Brazzaville) and Kenya; CTFT projects inthe Ivory Coast; research programmes of the Department ofTechnology and Fisheries Science of the Rhodes University,South Africa and through basic research programmes carriedout by the Department of Aquaculture and Inland Fisheries of
the Wageningen University in the Netherlands and otherUniversities and Institutes throughout the world.In the present paper an attempt is made tocompile and update available knowledge concerning therearing of Clarias gariepinus with particular emphasis toAfrican conditions.A number of the illustrations used in this paperhave been presented before in a publication of Viveen et al.,1985 and permission given to use the illustrations in thepresent handbook is gratefully acknowledged.
2.THE AFRICAN CATFISHgariepinus and Clarias anguillaris)2.1.(ClariasTaxonomyAlthough more than 100 different species of theGenus Clarias have been described in Africa, a recentsystematic revision based on morphological, anatomical andbiographical studies has been carried out by Teugels (1982a,1982b, 1984), who recognized 32 valid species. The largeAfrican species which are of interest for aquaculture belong tothe subgenus Clarias. In earlier systematic studies on thelarge African catfish species Boulenger (1911) as well asDavid (1935) recognized five species of within this subgenus.Both authors used morphological criteria such as form ofvomerine teeth, ratio of vomerine to premaxillary teeth bandand the number of gill rakers. The five species were;*****Clarias anguilarusClarias senegalensisClarias lazeraClarias mossambicusClarias gariepinusIn 1982 Teugels revised the subgenus Clariasand found only two species (C. gariepinus and C. anguillaris)if the number of gill rakers on the first branchial arch wasconsidered; for C. anguillaris the number of gill rakers wasrather low (14 to 40) while for C. gariepinus was relativelyhigh (20 to 100, Figure 1.).
120100No. of gill rakers80C. lazera60C. gariepinusC. mossambicus40C. anguillarisC. senegalensis2000100200300400500600Standard length (mm)Figure 1:Regression lines showing the correlationbetween standard length and number of gill rakers on the firstbranchial arch for the catfish species of the subgenus Clariasrecognized by Boulanger (1911) and David (1935). Source:Teugels, 1982b.2.2.Natural geographical distributionClarias gariepinus, which is widely considered tobe one of the most important tropical catfish species foraquaculture, has an almost Pan-African distribution, from theNile to West Africa and from Algeria to Southern Africa. Theyalso occur in Minor-Asia (Israel, Syria and South of Turkey).Clarias anguillaris has a more restricted distribution and isfound in Mauritania, in most West African basins and in theNile (Figure 2). In general C. gariepinus lives in most riverbasins sympatrically with C. anguillaris.
Figure 2:Geographical distribution of the African catfish.
3.BIOLOGY3.1.Description of the genus and speciesThe catfish genus can be defined as displayingan eel shape, having an elongated cylindrical body withdorsal and anal fins being extremely long (nearly reaching orreaching the caudal fin) both fins containing only soft fin rays(Figure 3). The outer pectoral ray is in the form of a spine andthe pelvic fin normally has six soft trays. The head isflattened, highly ossified, the skull bones (above and on thesides) forming a casque and the body is covered with asmooth scaleless skin. The skin is generally darkly pigmentedon the dorsal and lateral parts of the body. The colour isuniform marbled and changes from greyish olive to blackishaccording to the substrate. On exposure to light skin thecolour generally becomes lighterThey have four pairs of unbranched barbels,one nasal, one maxillar (longest and most mobile) on thevomer and two mandibulars (inner and outer) on the jaw.Tooth plates are present on the jaws as well as on the vomer.The major function of the barbels is prey detection.A supra-branchial or accessory respiratoryorgan, composed of a paired pear-shaped air-chambercontaining two arborescent structures is generally present.These arborescent or cauliflower-like structures located onthe secondhand forth branchial arcs, are supported bycartilage and covered by highly vascularised tissue which canabsorb oxygen from atmospheric air (Moussa, 1956). The airchamber communicates with the pharynx and with the gillchamber. The accessory air breathing organ allows the fish to
survive for many hours out of the water or for many weeks inmuddy marshes.Figure 3:Morphological characteristics of C. gariepinus.
The male and females of C. gariepinus can be easilyrecognized as the male has a distinct sexual papilla, locatedjust behind the anus. This sexual papilla is absent in females(Figure 4).Figure 4:Sexual characteristics of C. gariepinus.
3.2.HabitatClarias spp. inhabit calm waters from lakes,streams, rivers, swamps to floodplains, some of which aresubject to seasonal drying. The most common habitatsfrequented are floodplain swamps and pools in which thecatfish can survive during the dry seasons due to thepresence of the accessory air breathing organs (Bruton,1979a; Clay, 1979).3.3.Natural food and feedingAlthough numerous studies on the foodcomposition of C. gariepinus have been carried out, aconsistent pattern has not emerged and they are generallyclassified as omnivores or predators. Micha (1973) examinedcatfishes from the river Ubangui (Central African Republic)and found that C. lazera ( C. gariepinus) fed mainly onaquatic insects, fish and debris of higher plants. They alsofeed on terrestrial insects, mollusc and fruits.Similarly, Bruton (1979b) found that catfish inLake Sibaya (South Africa) fed mainly on fish or crustacea,and that terrestrial and aquatic insects were an important partof the diet of juvenile and adult fish which inhabit shallowareas. However, molluscs, diatoms, arachnids, plant debriswere the minor food items consumed in this lake.Munro (1967) studied the feeding habits of C.gariepinus in Lake McIIwaine (Zimbabwe) and found that feedcomposition changes as fish became larger. Diptera,particularly chironomid pupae, predominate in the diet of thesmallest group but become progressively less important withincreasing size. Zooplankton became more important withincreasing size and predominates in the diet of the largest
fish. Most of the minor food groups also showed aprogressive increase or decrease in importance in relation toincreasing size (Figure 5). The greater importance ofzooplankton in the diet of large fish was believed to be due tothe increased gape and number of gill rakers of the larger fish(Jubb, 1961; Groenewald, 1964); presumably resulting in amore efficient filter feeding.Figure 5:Apparent changes in the composition of themean daily ration of C. gariepinus in relation to increasingsize. Source: Munro, 1967.Spataru et al. (1987) studied the feeding habitsof C. gariepinus in Lake Kinneret (Israel) and found thatpreyed fish were the most abundant food component (81%)and constituted the highest biomass.In conclusion, we can consider C. gariepinus asa slow moving omnivorous predatory fish which feeds on avariety of foods items from minute zooplankton to fish half ofits own length or 10% of its own body weight.In order to feed on this wide variety of organisms in differentsituations C. gariepinus is equipped with a wide array ofanatomical adaptations for feeding under low visibility(Bruton, 1979b) including;
*A wide mouth capable of considerable verticaldisplacement for engulfing large prey or large volumes ofwater during filter feeding.*A broad band of recurved teeth on the jaws andpharyngeal teeth preventing prey from escaping.*An abundant network of sensory organs on thebody, head, lips and circumoral barbels. These barbels areextensively used for prey detection and fixation. Hecht andApplebaum (1988) found that C. gariepinus with barbels were22.6% more efficient at catching prey than those without. Thiscould indicate that tactile behaviour is important in the preycatching processes.*A wide, rounded caudal fin, typical for fish whichambush their prey.*Long gill rakers on the five branchial arches.*A short and dilatable oesophagus which opensinto a distinct muscular stomach (mechanical digestion) and asimple thin walled intestine.Slow, methodical searching is the normalpredatory tactic of C. gariepinus, with catfish grasping theirprey by suction; a negative pressure (suction) being createdby a sudden increase of the bucco-pharyngeal chamber.An important aspect of predation by C.gariepinus is their ability to switch feeding from one type ofprey to another. In Lake Sibaya (South Africa), catfish ignore(or cannot catch) fish prey during daylight and feed mainly oninvertebrates, which are abundant and relatively easy tocatch. By contrast, at night, when fish prey become morevulner
Artificial reproduction and pond rearing of the African catfish, Clarias gariepinus in sub -Sahara n Africa – A handbook FAO Fisheries Technical Paper. No 362. Rome, FAO. 1996. 73 p ABSTRACT The manual is based on the practical field experience of Gertjan de Graaf and Johannes Janssen on the artificial reproduction and
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