7

THE "CATFlSHAsIA" PROJECT: BACKGROUNDS, AIMS AND PROSPECTS

Marc Legendre

IRD (ex ORSTOM), Catfish Asia Project, InstalasiPenelitian Perikanan Air Tawar, Jalan. Ragunan-PasarMinggu; P.O. Box 7220/jkspm, Jakarta 12540, Indonesia

and GAMEr, B.P. 5095, 34033 Montpellier Cedex 1, France

Abstract

Catfishes, and in particular Clariidae and Pangasiidae, are important aquatic resources in Asia, wheretheir culture represented an annual production of about 124,000 t in 1993. In the clariids, this productionresults mostly from the use of F1 hybrids between the introduced African catfish (Clarias gariepinus) andvarious local clariid species. In the pangasiids, various culturing techniques were empirically developed forsome native species, whose juveniles are most often captured in the wild Further development of this catfishculture industry faces serious problems related to the poorly known systematic of these fish groups, thescarce knowledge of the biology and aquaculture potential of autochthonous species, the limitation of seedsupply and the declining performances reported in some cultivated stocks.

In this context, the "Catfish Asia" project which deals with the two catfish families, Clariidae andPangasiidae, has the main following goals:• To acquire a stronger knowledge of the biological diversity of SE Asian catfishes and to enhance its

utilisation through a correct identification and characterisation of valuable species, populations and strainsof aquaculture interest. This approach represents an important precondition to the sustainablemanagement of cultivated and natural stocks and to guide conservation efforts of these economicallyimportant resources. It will also contribute to a better knowledge of their phylogeographic relationships.

• To acquire sound biological bases for the development of catfish culture in the SE Asian region. Theevaluation of the aquaculture potential of the autochthonous species (diversification) and the optimisationof their rearing cycle (artificial propagation) through technologies adapted to the local conditions areessential elements for a better production in the future.The research work associates six institutes and laboratories from Indonesia, Vietnam, France and

Belgium. The specific objectives, general methodologies, first results and prospects of the project arepresented.

INTRODUCTION

Among the freshwater fish. the Siluriformes(including both autochthonous and exotic species)represent an important group in Asia. Severalspecies are actively exploited by fisheries and in avariety of aquaculture production systems.Although ranking beyond carps and tilapias, thetotal volume of cultured catfishes in Asia hasshown fast increase during the last 20 years andwas estimated around 124,000 t in 1993 (Csavas,1994). In the Lower Mekong Basin, catfishes ofthe clariid and pangasiid families are of particularsignificance for aquaculture. In 1993, theyrepresented an estimated annual production ofabout 21,000 t in Vietnam, 36,000 t in Thailandand 6,000 t (75 % of the total freshwater cultivated

fish production) in Cambodia. In Indonesia,clariids are the main cultivated catfishes (4,000 t in1992) but pangasiids present also a high potentialfor aquaculture, particularly in Sumatra andKalimantan (Sudarto and Sumastri, 1994).

Indigenous culture techniques were developedfor native species that are generally preferred bylocal consumers. However, in clariids, the actualtrend is to cultivate Fl hybrids between theintroduced African catfish (Clarias gariepinus)and various local species (c. macrocephalus or C.fuscus in Thailand or Vietnam, C. meladerma inIndonesia). These hybrids appear to combine theestimated flesh quality of local species and thefaster growth rate and disease resistance of theintroduced one. Because of the presence of avariety of pangasiid species and their omnivorous

8

nature, culture techniques can be adapted to thelocal conditions. Pangasiids are used both in small­scale or industrial production systems and can bereared in high-density cage culture, low inputpolyculture systems, integrated livestock/fishfarming or with human waste utilisation (Peignen,1993; Cacot, 1994; Csavas, 1994). The ability ofsome of these catfishes to undergo aerialrespiration allows their use for a valorisation ofpoorly oxygenated aquatic environments.

However, major constraints for furtherdevelopment and sustainable management ofcultivated and natural catfish resources stillremain. A part of the encountered problems islisted below, as they were identified in 1996.• Aquaculture has often been based on the

utilisation of introduced species while theknowledge on the biology and the potential ofautochthonous species remains scarce. As anexample, the African catfish Clarias gariepinushas been spread all over SE Asia where it iscultured either as such or after hybridisationwith local Clarias species. In Indonesia,although more than 10 pangasiid species werelisted from the ichthyofauna, the onlyPangasius cultured in this country remainedPangasius hypophthalmus, which was initiallyintroduced from Thailand

• Diversification of the cultivated species isrequired both for a better response of fishculturists to market demands, and for a better fitwith the diversity of habitats and consumerpreference. However, main limitations are thefollowings.~ The systematic of Siluriformes remains

poorly known in this region and informationon their genetic structure (species,populations) is very limited. In the pangasiidfamily, despite a systematic revision of thegroup (Roberts & Vidthayanon, 1991),numerous discrepancies were found inrecent descriptions of the fish fauna. Thiswas particularly the case for the Mekongdelta where the available informationrelative to taxonomy and even the number ofrepresented species was still inconsistent(Khoa & Huong, 1993; Lenormand, 1996).In Indonesia, the only local pangasiidspecies tested for aquaculture wasmisidentified as P. pangasius and remainedto be correctly named. For SE Asian c1ariids,the situation was even more confusing as themost recent revision was made by David in

1935. In the absence of reliableidentification keys, cultured species areoften misidentified. This situation impairs acomprehensive view of the culture potentialof these fishes and a correct interpretation ofthe information published on their biologyand culture.

~ In most cases seed supply is impaired by theabsence of reproductive control in captivityand by fluctuating or limited natural wildjuvenile resources (Csavas, 1994; Cacot,1994).

• Declining performances in cultured fishes havebeen reported in several areas in SE Asia (Mainand Reynolds, 1993).

• Introductions of exotic species for pure cultureor hybridisation with native species couldinduce diseases due to parasites (Welcomme,1988; Konelat, 1990) and genetic impacts onnative gene pools (Hindar et al., 1991).1berefore, the precise description and

characterisation of species, populations and strainsin these fish groups represent a condition sine quanon to the sustainable management of theircultivated and natural stocks and to guideconservation efforts of these economicallyimportant resources. They should also contribute toa better knowledge of their phylogeographicrelationships.

The sound evaluation of the aquaculturepotential of the autochthonous species(diversification) and the optimisation of theirrearing cycle (particularly artificial propagation)through technologies adapted to the localconditions appears as essential elements for abetter production in the future.

These topics were retained has the main goalsof the "Catfish Asia" project, which focuses on thetwo main catfish families of economic importance,the Clariidae and Pangasiidae. The genesis,specific objectives, general methodologies, firstresults and expected outcomes of the project arepresented in the present paper.

GENESIS OF THE PROJECT ANDPARTNERSHIP

The first contact between the European andAsian partners today associated in the "CatfishAsia" project took place in 1992 during aprospective mission of two of us in the SoutheastAsian region (Lazard & Legendre, 1993). This first

contact allowed the identification of research fieldsrelated to fish biology and culture, and partnerinstitutions to develop collaborative programmes.The cooperation was initially engaged by exchangeof scientists and students between France, on oneside, and Vietnam and Indonesia, on the other side.

In Vietnam., inquiries were made on catfishproduction systems (peignen, 1993; Bazir, 1994;Cacot, 1994) and a preliminary study on thesystematic, biology and aquaculture potential ofpangasiid species from the Mekong Delta wascarried out (Lenormand, 1996). Starting from1994, the French Ministry of Foreign Affairssupported a collaborative programme on thecontrol of reproduction of Pangasius bocourti,associating two French (CIRAD and IRD) andthree Vietnamese institutions (the Can ThoUniversity (CTU), the University of Agronomyand Forestry (UAF) and the AGIFISH Company).This programme led to the very first spawn of thisspecies in captivity, obtained in May 1995. Itrepresented an important success as, until this date,the millions of P. bocourti juveniles necessary tosustain the 15,000 tonnes of annual aquacultureproduction of this species in the Mekong deltawere entirely dependent on captures from the wild

The study of populations genetic of SE AsianClarias species was also started in 1995 in acooperation between IRD, the Central ResearchInstitute for Fisheries (CRIFI-RIFF) based inJakarta, Indonesia, and the University MontpellierIT.

These different activities and their resultsprovided a solid basis and moovated thepreparation of a more ambitious collaborativeresearch programme on the biodiversity andaquaculture of catfishes in SE Asia. SinceNovember 1996, this programme, abbreviated as"Catfish Asia" I, is coordinated by IRD andsupported by the European Commission. Itassociates 6 research institutions, from France(IRD and CIRAD), Belgium (Musee Royal del'Afrique Centrale and Katholieke UniversiteitLeuven), Indonesia (CRIFI-RIFF) and Vietnam(CTU) (Fig. 1).

A part of the research is also conducted in closecooperation with the AGIFISH Company inVietnam and the services of the DirectorateGeneral for Fisheries in Indonesia, allowing real

1 Full title of the project: Characterisation; utilisationand maintenance of biological diversity for thediversification and sustainability of catfish culture inSouth-East Asia.

9

possibilities for a rapid and efficient transfer ofresults from research to the production sector andfish farmers.

OBJECTIVES OF THE "CATFISH ASIA"PROJECT

In order to enhance the utilisation of thebiological diversity of the local freshwaterichthyofauna, acquire sound biological bases forthe development of aquaculture, provide anappraisal of the present situation in order to guidesustainable management of cultivated and naturalfish resources, and strengthen North-South-Southcooperation between the European Union,Indonesia and Vietnam by the transfer andexchange of technology, the project aims at thefollowing specific objectives:• To characterise species, populations and strains

of autochthonous Clariidae and Pangasiidaecatfishes for:~ A thorough knowledge of their taxonomy

and appraisal of their phylogeny andzoogeography.

~ A general inventory of available resourcesthat could be used for culture.

• To contribute to the knowledge of their lifehistory.

• To implement monitoring tools that could beused for the analysis of populationmicrostructuration and monitoring of geneticdiversity in cultivated fish stocks (Le.development of DNA microsatellite loci).

• To assess and compare the aquaculture potentialof species, populations and hybrids in thePangasiidae and Clariidae.

• To develop artificial propagation and culturetechniques adapted to local conditions for sometarget species for which captive broodstock canbe available:~ Identification of the environmental

requirements to attain full sexual maturityunder rearing conditions and optimisation ofinduced breeding and artificial fertilisationprocedures.

~ Assessment of some nutritional, behaviouraland environmental requirements of larvaland juveniles stages and optimisation oflarval rearing methods.

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The research work is divided into two majorparts:

The first part aims at the identification andcharacterisation of species and populations ofactual or potential interest for aquaculture. Threecomplementary approaches are used:I) morphometric analysis, 2) estimation of geneticvariation, and 3) characterisation of gill parasitecommunities.• The morphometric analysis consists in a

number of measurements, meristic counts andspecial morphological observations taken onrepresentative samples of species orpopulations. This part of the work should resultin correct and detailed descriptions of thedifferent species, populations or hybrids.

• The estimation of genetic variation includesdifferent techniques adapted to the researchgoals: protein electrophoresis, mitochondrialDNA analysis and microsatellite DNA analysis.~ Protein electrophoresis is the most suited to

examine evolutionary relationships within agreat number of species belonging to thesame or different genera. It gives rapidlyaccurate data in systematic investigations.However, in closely related taxa, differencesin variation in allelic frequencies are oftenindicative but not sufficient to assign asingle fish to a particular stock.

~ The restriction endonuclease analysis ofmitochondrial DNA (mt-DNA) is a moreaccurate approach for population analysis atthe intraspecific level. As the differences inmt-DNA base sequences (generated bymutation) are transmitted maternally withoutrecombination, the mt-DNA analysisprovides a strong support for stockidentification and zoogeography.

~ 'The microsatellites DNA analysis allowsmuch greater stock discrimination and isused as a complementary approach to screenwild populations for overall geneticvariation.

The investigation of intraspecific differentiationmay allow the identification of differentiatedpopulations of potential interest for future use inaquaculture. In addition, the development of DNAmicrosatellite loci provides highly discriminatingtools which could be used subsequently for thecharacterisation and monitoring of geneticdiversity in cultivated fish stocks.• The characterisation of gill parasite

communities (Monogenea) completes the

11

genetic and morphometric analyses andprovide complementary elements for the studyof host's phylogeography. Monogenea have,toward their hosts, a specificity which isgenerally oioxenous (one species of parasite ispresent on only one host species). When thespecificity is larger (stenoxenous) it is eitherdue to lateral transfer or to genetic relatednessof the hosts. Parasites are identified bymorphological studies (optic microscopy) oftheir sclerotized parts (genital and haptoralapparatus).

For these studies, representati ve fish samplesfrom wild or culture origin are collected at theregional scale. 'The morphology, genetics andparasitology of this material are studiedconcurrently. During the sampling campaigns,observations are also made on the biological traits(reproductive strategies, feeding habits...) of thecollected species.

The second part of the research is orientedtoward a diversification of the cultivated species,the identification of the best performing ones(including hybrids) and an optimisation of theculture practices (particularly artificialpropagation).• The global and comparative evaluation of the

aquaculture potential of pangasiid species iscarried out following a two-stage procedure(Legendre, 1992; Lenormand, 1996):~ On the most objective biological and

economical criteria, a preliminary screening,the preselection stage, aim to retain thosespecies that, among the entire group, presentthe greatest potential for a given type ofaquaculture.

~ 'Then, in the selection stage, an evaluation ofthe aquaculture performances of thepreselected species is made in culture trials.

The choice of an aquaculture candidate dependsdirectly on biological characteristics of the speciesand on the environment, as well as on theeconomic and cultural context of the areas orcountries concerned (e.g. pangasiids are moreappreciated in Sumatra and Kalimantan than inJava). 'The preselection is based on informationobtained from field sampling, market studies andliterature analysis. In this view, the maximal sizeof species represents a useful biological criterion,both in regards to specific market demand for fishsize and as a rapid estimator of growth rate(Legendre & Albaret, 1991).

12

The culture trials are carried out inexperimental aquaculture stations from juvenilescaught in the wild Three main characteristics arestudied: survival, growth and sexual maturation.The fish are generally tagged for individualidentification.

In the clariids, the research work is mostlyoriented toward a comparative evaluation ofzootechnical performances ofdifferent hybrids andof their parental species. The following criteria aregenerally considered: survival, growth, age/size atfirst sexual maturity, gonadal development,viability of the gametes and possibilities ofobtaining viable F2 or back cross fry. Despite anincreasing use of Clarias hybrids in SE Asianaquaculture, there is a lack of reliable and detaileddata on their biological traits and zootechnicalperformances in comparison to parental species.Similarly, preliminary investigations onhybridisation have been started in the pangasiids.

The establishment of reliable artificialpropagation techniques is sought in pangasiidsactually identified for their interest in aquaculture(particularly P. djambal in Indonesia, P. bocourtiin Vietnam and P. hypophthalmus in bothcountries). This task includes three complementaryresearch actions.• The identification of the environmental

requirements to attain full sexual maturationunder rearing conditions is done throughinvestigations on the gonadal development oftagged brooders kept in earthen ponds ancVorfloating cages. The sexual maturity of thefemales is regularly followed using especiallythe oocyte diameter and the position of theirgerminal vesicles determined after intraovarianbiopsy. In males, spermiation, volume ofcollected semen and motility of spermatozoaare used as the main maturity criteria.

• The optimisation of the induced breedingprocedures involves the following steps:a) defining selection criteria for receptivebrooders, b) establishing efficient hormonaltreatments to induce oocyte maturation andovulation, c) determining the optimal latencyperiod between injection and stripping of ovaand, d) proposing appropriate standardisedtechniques of artificial fertilisation and eggincubation.

• The optimisation of larval rearing methodsrequires precise knowledge on larval biologyand the development of specifically adaptedlarval rearing systems. Adequate preys, feeding

requirements, behavioural particularities (e.g.occurrence or not of cannibalism) andappropriate weaning time are characteristicsparticularly considered.Finally for some Pangasius species already

used in aquaculture, two supplementary topicswere added to the initial objectives of the project:the evaluation of the nutritional requirements ofjuveniles and a survey of the main pathologicalproblems encountered in various culture systems.

FlRST RESULTS AND PROSPECTS

In 1998, at its mid-term, the Catfish Asiaproject has already led to many significant results,in terms of both basic and applied research. Theseresults are presented into details all along thecontributions compiled in this volume. Some of themain aspects and their implications in terms offurther research and development are commentedhereafter.• Representative fish samples from wild or

culture origin have been collected from thefollowing areas: Java, Sumatra, Kalimantan, theLower Mekong Basin (particularly MekongDelta) and the Chao Phraya River Basin. Thesecampaigns helped to precise the zoogeographyof several taxa. Supplementary samplingcampaigns remain to be done from other areasin order to complete the collection of speciesand improve the assessment of theirphylogeography.

• In the pangasiids, 18 of the 21 nominal speciesdescribed by Roberts and Vidthayanon (1991)were already collected and geneticallyanalysed. Considering the observed geneticdistances, the results suggest that several groupspreviously recognised as possible subgenus ofPangasius should be elevated at the genuslevel. Two possible new species, Pangasius sp1and sp2 were also identified. As no specimensof P. pangasius could be collected yet, theexact status of Pangasius sp1 remains unclear.Up to now, it was however misidentified asP. djambal. A detailed morphometric analysisof all specimens collected remains to be done inthis family. The fact that Pangasius spl wascollected mostly in the estuarine part of therivers (in the Mekong Delta, Sumatra andKalimantan) confer to this fish a specialinterest, as it might represent a candidate forbrackish water aquaculture both in Vietnam and

Indonesia.In the clariids, the morphometric analyses andgenetic investigations carried out (not allpresented in this volume) confirm the needs fora systematic revision of this group, as far as theAsian species are concerned.The establishment of reliable identificationkeys in these two families should be a majorobjective of the second half of the project.

• The parasitic analysis of pangasiid speciesshowed the occurrence of more than fiftyspecies of gill monogenea, of which 3 or 4 onlywere already described. An important work ofdescription of the newly discoveredmonogenean species is currently carried out. Asabout 80% of these monogenea are hostspecific, the analysis of monogenean parasitecommunities at the host species or populationslevels will represent a useful complement to themorphometric and genetic studies for theinference of hosts phylogeny.

• Several functional new microsatellite markershave been developed in both C. batrachus andP. hypophthalmus. Some markers previouslydeveloped for C. gariepinus were alsooperational in these two species. In a shortterm, these markers will be used for themolecular identification of wild caught Clariasspecies in Sumatra and the study of their small­scale genetic structure. Samples of culturedC. gariepinus from various Asian localities willbe also analysed to identify their level ofinbreeding.

• Among the 21 recognised species of Pangasiids(now probably 23), only 2 of them (P. bocourtiand P. hypophthalmus) are actually cultured ona large scale in SE Asia. Investigations werealso performed on P. gigas in Thailand, initiallyfor a conservation purpose.Assuming the validity of the two new speciesdiscovered during the project, 13 pangasiids arepresent in Indochina (Mekong Basin) and 13 inthe Indo-Malay Archipelago (5 endemic to theBorneo Island); 5 species are common to bothgeographical areas. Due to their relatively smallsize, 5 species do not seem to present muchinterest for culture in comparison to the otherspangasiids: P. macronema, P. micronema,P. pleurotaenia, P. polyuranodon andHelicophagus waandersii. Among the speciesreaching larger sizes, captive stocks of 5 ofthem have been constituted during the first halfof the project in order to evaluate their

13

aquaculture potential: P. conchophilus,Pangasius sp 1 and P. lamaudii in Vietnam, andP. nasutus and P. djambal in Indonesia. Thelatter species already showed a much fastergrowth rate than P. hypophthalmus. BesidesPangasius sp 1, another species, P. krempfi,found in the estuaries of the Mekong Delta,may present a particular interest for brackishwater culture and should be investigated.

• An important part of the work has been orientedtowards an optimisation of induced breedingand larval rearing procedures of species alreadyreproduced in captivity (P. bocourti andP. hypophthalmus). Significant progresses wereobtained for both species and reliablemethodologies were established. taking intoaccount the seasonal variations of reproduction,the hormonal treatments applied and theviability of gametes and embryos. In P.hypophthalmus, the possibility of an all yearround production of fry was demonstrated, andthe survival and growth of larvae in controlledenvironment were strongly improved by usingappropriate prophylactic treatments and feedingstrategies. The transfer of these optimisedartificial propagation methods to fish farmersalready started in Vietnam and in Indonesia.

• Besides these two species, the reproduction incaptivity of P. conchophilus and Pangasius sp 1in Vietnam and of P. djambal in Indonesia wasalso obtained for the first time from wildspecimens acclimatised to culture conditions.Although artificial propagation techniques stillneeds to be specifically adapted for thosefishes, these first successes now open strongopportunities for the development of their usein aquaculture.

• The availability of juveniles in some speciesalso permitted to start investigations on theirfeeding strategies and nutritional requirements.The clear tendency of P. bocourti juveniles tostart fat deposition even when fed at a lowfeeding rate and the apparent inverserelationship between fat deposition and gonadmaturation in adult females of this species areaspects requesting further studies.

• Hybridisation is a manipulation permitted bythe control of reproduction in captivity. Severalcrosses were tested in the clariids and thereciprocal hybrids between P. bocourti andP. hypophthalmus also proved to be viable inVietnam. However, although hybrids maypresent several valuable qualities for

14

aquaculture and are always fascinating toproduce, evaluation of their performancesshould be reserved to research station withclosed facilities. Uncontrolled hybridproduction trials on fish farms have been madeboth in Vietnam and Indonesia between variouspangasiid species. The risk that individualscould escape from fish farms is high and mayhave serious impacts on the native gene pools.Therefore the production of hybrids inaquaculture should be considered only after afull evaluation of their performances incomparison to those of their parental speciesand an assessment of their possible fertility.The possibility or not of making hybridsbetween two species is also a good indication oftheir genome compatibility. The fact that thehybridisation between C. gariepinus andC. batrachus was successful in Bangladesh andneither in Indonesia nor in Vietnam, suggeststhat the nominal species C. batrachuscorresponds to a species complex. It should benoticed that high genetic divergences were alsoobserved between the low and highlandsC. batrachus populations of Sumatra. Thereforethe actual status of this important species foraquaculture clearly requests furtherinvestigations.The final workshop of the "Catfish Asia"

project is planned in May 2000 and will beorganised in Bogor, Indonesia. A full synthesis ofthe results obtained during the 4 years of thiscollaborative programme will be presented at thisoccasion.

REFERENCES

Bazir A (1994) Caracteristiques de la piscicultureen cages jlottantes sur deux lacs debarrage du sud du Viet Nam. DocumentORSTOM, Montpellier, France, n'Tl, 107p. + annexes.

Cacot P. (1994) Presentation de la pisciculture encages jlottantes dans le sud Viet Nam.Caracteristiques de l'elevage sur le Mekong dePangasius pangasius. CIRAD-EMVT,Montpellier, France, 107 p.

Csavas I. (1994) Status and perspectives ofculturing catfishes in East and South-East Asia.FAO Aquaculture Newsletter, 8, 2-10.

Hindar K., Ryman N. & Utter F. (1991) Geneticeffects of cultured fish on natural fish

populations. Can. J. Fish. Aquat. Sci., 48, 945­957.

Khoa T.T. & Huong T.T. (1993) Identification offreshwater fish species of the Mekong Delta.Can Tho University, Can Tho, Vietnam, 361 p.(in Vietnamese).

Kottelat M. (1990) Synopsis of the endangeredBuntingis (Osteichthyes: Adrianichthyidae andOryziidae) of Lake Poso, Central Sulawesi,Indonesia, with a new reproductive guild anddescription of three new species. Ichthyol.Explor. Freshwaters, 1,49-67.

Lazard J. & Legendre M. (1993) Compte-rendu demission en Asie du sud-est - Aquaculturecontinentale. CIRAD-EMVT I ORSTOM,GAMET, Montpellier, France, 44 p.

Legendre M. (1992) Potentialites aquacoles desCichlidae (Sarotherodon melanotheron, Tilapiaguineensis) et Clariidae (Heterobranchuslongifilis) autochtones des lagunes ivoiriennes.Paris: ORSTOM, TOM 89, 83 p. + ann.

Legendre M. & Albaret J.J. (1991) Maximalobserved length (MOL) as an indicator ofgrowth rate in tropical fishes. Aquaculture, 94,327-341.

Lenormand S. (1996) Les Pangasiidae du Delta duMekong: description preliminaires despecheries, elements de biologie et perspectivespour une diversification des elevages. ENSA­Rennes et ORSTOMlGAMET, France, 83 p.

Main K.L. & Reynolds E. (eels) (1993) Selectivebreeding of fishes in Asia and the United States.Proceedings of a workshop in Honolulu,Hawaii, May 3-7 1993.267 p.

Peignen A (1993) Pisciculture en etang au sudViet Nam. Bourse pour I'Asie 19931LVMH,GAMET, Montpellier, France, 33p.

Roberts T.R. & Vidthayanon C. (1991) Systematicrevision of the Asian catfish familyPangasiidae, with biological observations anddescriptions of three new species. Proceedingsof the Academy of Natural Sciences ofPhiladelphia, 143,97-144.

Sudarto S. & Sumastri S. (1994) Prospects of usingcatfish hybrids for aquaculture in Indonesia.Intemational workshop on the biological basesfor aquaculture of Siluriformes. (Abstract),p.60.

Welcomme R.L. (1988) International introductionsof inland aquatic species. FAO Fish. Tech.Pap., 294, 318 p.

3

CONTENTS

Page

FOREWORD 1

CONTENTS 3

CONTEXTS AND RESEARCH GOALS

Legendre M. The Catfish Asia project: backgrounds, aims and prospects.--------------------------- 7

Lazard J. Interest of basic and applied research on Pangasius spp. for aquaculture in theMekong Delta: situation and prospects.-------------------------------------------------------- 15

Sadili D. Marketing of pangasiid catfishes in Java and Sumatra, Indonesia.----------------------- 21

BIOLOGICAL DIVERSITY

CHARACTERlSA110N OF SPECIES, POPULA110NS AND STRAINS

Teugels G.G., Legendre M. & Hung L.T. Preliminary results on the morphologicalcharacterisation of natural populations and cultured strains of Clarias species(Siluriformes, Clariidae) from Vietnam.--------------------------------------------------------- 27

Teugels G.G., Gustiano R., Diego R., Legendre M. & Sudarto. Preliminary results on themorphological characterisation of natural populations and cultured strains of Clariasspecies (Siluriformes, Clariidae) from Indonesia.-------------------------------------------- 31

Pariselle A. & Komarudin O. First results on the diversity of gill parasites of some catfisheshost species in South East Asia.------------------------------------------------------------------ 37

Pouyaud L., Hadie W. & Sudarto. Genetic diversity among Clarias batrachus (Siluriformes,Clariidae) populations from the Indochina Peninsula and Indonesia Archipelago.----------- 43

Pouyaud L., Gustiano R. & Legendre M. Phylogenetic relationships among pangasiid catfishspecies (Siluriformes, Pangasiidae). -------------------------------------------------------------- 49

Volckaert F., Hellema~ B. & Pouyaud L. Preliminary data on genetic variation in the genusClarias and Pangasius on the basis of DNA microsatellite loci.---------------------------- 57

BID-ECOLOGY

Thuong N.V., Hung H.P., Dung D.T. & Kha L.A. Preliminary data on species compositionand distribution of pangasiid catfishes (Siluriformes, Pangasiidae) in the lower MekongFtiver basirL-------------------------------------------------------------------------------------- Eil

AQUACULTUREINOPTIMISATIONANDDIVERSIFICATIONPRODUCTION

REPRODUC110N

Cacot P. Description of the sexual cycle related to the environment and set up of the artificialpropagation in Pangasius bocourti (Sauvage, 1880) and Pangasius hypophthalmus(Sauvage, 1878), reared in floating cages and in ponds in the Mekong delta.--------------- 71

Legendre M., Subadgja J. & Slembrouck J. Absence of marked seasonal variations in sexualmaturity of Pangasius hypophthalmus brooders held in ponds at the Sukarnandi station(Java, Indonesia).---------------------------------------------------------------------------------- 91

Legendre M., Slembrouck J. & Subadgja J. First results on growth and artificial propagationof Pangasiusdjambal in Indonesia.--------------------------------------------------------------- 97

4

Xuan L.N. & Liem P.T. Preliminary results on the induced spawning of two catfh species,Pangasius conchophilus and Pangasius sp l, in the Mekong delta.----------------------------- 103

Kristanto A.H., Subadgja J., Slembrouck J. "& Legendre M. Effects of egg incubationtechniques on hatching rates, hatching kinetics and survival of larvae in the Asian catfishPangasius hypophthalmus (Siluriformes, Pangasiidae).---------------------------------------- 107

Campet M., Cacot P., Lazard J., Dan T.Q., Muon D.T. & Liem P.T. Egg quality of an Asiancatfish of the Mekong River (Pangasius hypophthalmus) during the process of maturationinduced by hCG injections.-------------------------------------------------------------------------- 113

Legendre M., Slembrouck J., Subadgja J. & Kristanto A.H. Effects of varying latencyperiod on the in vivo survival of ova after Ovaprim- and hCG-induced ovulation in theAsian catfish Pangasius hypophthalmus (Siluriformes, Pangasiidae).------------------------- 119

LARVAL BIOWGY AND REARING

Hung L.T., Tuan N.A., Hien N. V. & Cacot P. Larval rearing of the Mekong catfish,Pangasius bocourti (Siluriformes, Pangasiidae): Artemia alternative feeding and weaningtime.--------------------------------------------------------------------------------------------------- 127

Slembrouck J., Hung L.T., Subadgja J. & Legendre M. Effects of prey quality, feedinglevel, prey accessibility and aeration on growth and survival of Pangasius hypophthalmuslarvae (Siluriformes, Pangasiidae).--------------------------------------------------------------- 137

Subadgja J., Slembrouck J., Hung L.T. & Legendre M. Analysis of precocious mortality ofPangasius hypophthalmus larvae (Siluriformes, Pangasiidae) during the larval rearing andproposition of appropriate treatments.-------------------------------------------------------------- 147

NUTRI110N, FEEDING AND GROWTH

Hung L.T., Tuan N. A., Phu N.V. & Lazard J. Effects of frequency and period of feeding ongrowth and feed utilisation on Pangasius bocourti in two Mekong catfishes, Pangasiusbocourti (Sauvage, 1880) and Pangasius hypophthalmus (Sauvage, 1878).------------------ 157

Hung L.T., Lazard J., Tu H.T. & Moreau Y. Protein and energy utilisation in two Mekongcatfishes, Pangasius bocourti and Pangasius hypophthalmus.--------------------------------- 167

Phuong N.T. & Hien T.T.T. Effects of feeding level on the growth and feed conversionefficiency of Pangasius bocourti fingerlings.--------------------------------------------------- 175

Phuong N.T., Thi M.V. & Hang B.T.B. The use of plant protein (soybean meal) as areplacement of animal protein (fish meal and blood meal) in practical diets for fingerlingsof Pangasius bocourti.---------------------------------------------------------------------------- 179

Liem P.T. & Tu H.T. Rearing of Pangasius bocourti fry (Siluriformes, Pangasiidae) feddifferent diets in concrete tanks.------------------------------------------------------------------- 187

HYBRIDS EVALUA110N

Kiem N.V. & Liem P.T. Some biological characteristics of Clarias batrachus and Preliminaryresults of the hybridisationbetween Clarias batrachus x Clarias gariepinus.-------------- 191

Lenormand S., Slembrouck J., Pouyaud L., Subadgja J. & Legendre M. Evaluation ofhybridisation in five Clarias species (Siluriformes, Clariidae) of African (c. gariepinus)andAsian origin (c. batrachus, C. meladerma; C. nieuhofii andC. teijsmanni).------------- 195

Minh L.T. Preliminaryresults on the relationship between growing stage and body compositionin Clarias macrocephalus, Clarias gariepinus and their hybrid (c. macrocephalus femalex C. gariepinus male).--------------------------------------------------------------------------- 211

PATHOWGY

Komarudin O. Preliminary observations on the infection of the gills of cultivated Pangasiushypophthalmus by Monogenea.---------------------------------------------------------------------- 217

Supriyadi H., Komarudin O. & Slembrouck J. Preliminary study of the source of Aeromonashydrophila infection on Pangasius hypophthalmus larvae.----------------------------------- 219

Dung T.T. & Ngoc N.T.N. Preliminary results of the study of parasitic and red spot diseases onhigh economical valuable catfish species in the Mekong Delta.------------------------------- 223

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