Introduction of jundia Rhamdia quelen (Quoy &

Gaimard) and Nile tilapia Oreochromis niloticus

(Linnaeus) increases the productivity of carp

polyculture in southern Brazil

Leonardo Bolognesi da Silva1, Leonardo Jose¤ Gil Barcellos2, Rosmari Mezzalira Quevedo3,Silvia Maria Guimara� es de Souza1, Alexandre de Mello Kessler1, Luiz Carlos Kreutz2, Filipe Ritter4,Jovani AntoŒ nio Finco4 & Alexandra Calliari Bedin4

1Veterinarian, Universidade Federal do Rio Grande do Sul, Departamento de Zootecnia, Setor deAquacultura. Avenida Bento

Gonc� alves, PortoAlegre, RS, Brazil2Veterinarian, Professors. Universidade de Passo Fundo (UPF), Curso de MedicinaVeterinaŁ ria. Campus I, Passo Fundo, RS,

Brazil3Biologist, UPF, Passo Fundo, RS, Brazil4Undergraduate Students of Veterinary Medicine, UPF, Passo Fundo, RS, Brazil

Correspondence: Dr L J G Barcellos, Faculdade deAgronomia e MedicinaVeterinaŁ ria, Universidade de Passo Fundo, Campus I, Cx Postal

611, Bairro Sa� o Jose¤ . CEP 99001-970^Passo Fundo^RS^Brasil. E-mail: lbarcellos@upf.br

Abstract

Fish polyculture is based on the assumption that eachspecies has its own feeding niche and may increasethe maximum standing crop of a pond by exploringawider range of available food and ecological niches.In order to identify the better species ratio and to in-troduce jundia (JN) (Rhamdia quelenQuoy &Gaimard)and Nile tilapia (NT) (Oreochromis niloticus Linnaeus)in to the carp polyculture practiced in South Brazil, a162-day experiment was conducted, in 12 250-m2

earthen ponds (1.2m deep). Treatment I (T-I) con-tained 35% common carp, Cyprinus carpio (L.) (CC);35% grass carp, Ctenopharyngodon idella Valen-ciennes (GC); 15% silver carp, Hypophthalmichthysmolitrix Valenciennes (SC); and 15% bighead carp,Aristichthys nobilis Richardson (BC). Treatment II (T-II) consisted of three ponds stocked at the followingratio: 17.5% CC, 35% GC, 15% SC, 15% BC and 17.5%JN.Treatment III (T-III) consisted of three ponds with35% CC,35% GC,7.5% SC,7.5% BC and15%NT.Treat-ment IV (T-IV) consisted of three ponds with 17.5%CC, 35% GC, 7.5% SC, 7.5% BC%, 17.5% JN and 15%NT. No signi¢cant correlation was found betweenthe treatments with di¡erent species ratio and waterquality parameters. The ¢nal weight of di¡erent

species, in di¡erent treatments, was statisticallydi¡erent. The major result was the clear positivee¡ect on growth parameters observed by the intro-duction of JN and/or NT in to the carp polyculture.The yield per hectare was 2083.33 � 183 kgha�1 forpolyculture with carp species; 2476.67 � 139.88 kgha�1 following the introduction of JN only;2801.67 � 111.42 kgha�1 for isolated introductionof NT; and 2506.67 � 422.31kg ha�1 for simulta-neous introduction of JNand NT.The introduction ofJN and/or NT had a positive e¡ect on growth para-meters when compared with carp-only polyculture.The reduction in CC ratio also had a positive e¡ecton growth parameters.

Keywords: polyculture, growth, carp, jundia, Niletilapia

Introduction

Carp polyculture is one of the most important ¢shproduction systems around the world. The culture ofdi¡erent carp species in the same pond optimizes theutilization of food available in the ecological nichesof the pond ecosystem (Kestmont 1995) due to the

Aquaculture Research, 2008, 39, 542^551 doi:10.1111/j.1365-2109.2008.01912.x

r 2008 TheAuthors542 Journal Compilationr 2008 Blackwell Publishing Ltd

assumption that each carp species has its ownfeeding niche, which does not completelyoverlap feeding niches of other species (Rahman,Ver-degem, Nagelkerke,Wahab, Milstein & Verreth 2006)As observed by Silva, Barcellos, Quevedo, Souza,Kreutz, Ritter, Finco and Bedin (2006), polycultureincreases productivity by allowing a more e⁄cientutilization of the ecological resources in themultispecies aquatic environment. Thus, stockingtwo or more complementary species can increasethe maximum standing crop of a pond by allowing awider range of available food and ecologicalniches.Themajor problem found in carp polyculture prac-

ticed in southern Brazil is the low acceptance of dif-ferent carp species viz., common carp (CC), grasscarp (GC), silver carp (SC) and bighead carp (BC). Inthis scenario, the introduction of other species witha higher market price and better acceptance by con-sumers seems to be the best alternative to improve¢sh production. Jundia (JN, Rhamdia quelen Quoy &Gaimard), a native omnivore bagrid ¢sh, but with apreference for protein of animal sources (Gomes,Golombieski, Chippari-Gomes & Baldisserotto 2000),and the well known omnivorous and ¢ltrating ¢sh,the Nile tilapia (NT, Oreochromis niloticus L.), werethe species chosen for co-cultivation with thedi¡erent carp species.The carp polyculture system is themost commonly

used in the region of study. According to theBrazilian Institute for Environment and RenewableResources (IBAMA ^ Instituto Brasileiro doMeioAmbiente e dos Recursos Naturais RenovaŁ veis),in 2005 the Rio Grande do Sul state produced23314 metric tonnes of freshwater ¢sh and 90% ofthese ¢sh were carps from polyculture systems(20982 T), 8% NT (1884.5 T) and 1.54% JN (358 T).Combined, these three ¢sh species represent 99.54%of the total freshwater ¢sh production in Rio Grandedo Sul.Thus, the aimof the present studywas to eval-uate the introduction of two more valuablespecies into the traditional polyculture practiced insouthern Brazil.

Methods

This study was conducted from November 2005 toMay 2006 at the facilities of the Universidade dePasso Fundo (UPF), Rio Grande do Sul (687m abovesea level), Brazil.

Fish and culture techniques

The ¢sh used in the present study were JN (R. quelen)and carps (Cyprinus carpio, Ctenopharyngodon idella,Hypophthalmichthysmolitrix andAristichthys nobilis),bred and maintained in the Aquaculture Laboratoryof the UPF, and NT (O. niloticus) acquired from localsuppliers. The initial meanweight of ¢ngerlings was:CC,0.68 � 0.21g; GC,1.84 � 0.37 g; BC,0.51 � 0.16 g;SC, 0.65 � 0.11g; JN, 1.4 � 0.33 g; and NT,1.33 � 0.2 g. Fingerlings were cultivated using fourdi¡erent proportions of carps (GC, SC, BC and CC),NTand JN (Table1).The productivity, climate and water quality para-

meters were evaluated over a cycle of 162 days in thesummer season. The experiment was carried out intwelve 250m2 earthen ponds (1.2m deep each). Theponds, rectangular in shape, were prepared by drain-ing and sun drying for 30 days and then limed withCaMg(CO3)2 (6 t ha�1). This relatively high rate oflime was applied due to the acid soil in the experi-mental region, whichvaried from 4.4 to 4.6.The basicfertilization programme consisted of chicken litter(1.2% N,1.8% P2O5, 0.6% K2O5, 27.6% organic matterand 30.7% dry matter), spread on the bottom of theponds at a rate of 4.8 t ha�1, based on our observa-tions and on data given by Bhakta, Sarkar, Jana andJana (2004). The ponds were then ¢lled with water(up to 40 cm in depth). After 4 days, the level of waterin all ponds was increased to 1m and ¢sh were thenintroduced. The water inlet and outlet pipes wereprotected with nylon enclosures to prevent entry ofunwanted species and escape of cultured ¢sh. Thewater in£ux rate was approximately 6 Lmin�1.Tomaintain an ideal population of phyto- and zoo-

plankton, measured indirectly by the Secchi disc

Table 1 Stocking rate of di¡erent ¢sh species in theexperimental treatments

Specie

Treatments (species rate, %)

T-I T-II T-III T-IV

Stocking density (fingerlingsha�1)

5000 5000 5000 5000

Cyprinus carpio 35 17.5 35 17.5

Ctenopharingodon idella 35 35 35 35

Hipophtalmicthys molitrix 15 15 7.5 7.5

Aristichthys nobilis 15 15 7.5 7.5

Rhamdia quelen 17.5 17.5

Oreochromis niloticus 15 15

T-1, treatment-1.

Aquaculture Research, 2008, 39, 542^551 Jundia and Nile tilapia increases carp polyculture performance L B da Silva et al.

r 2008 TheAuthorsJournal Compilationr 2008 Blackwell Publishing Ltd, Aquaculture Research, 39, 542^551 543

transparency, additional application of 800 kg ha�1

of chicken litter and inorganic fertilizers, at a rate of9 kg ha�1 of triple superphosphate (TSP) and9 kg ha�1of urea, was performed biweekly.At the beginning of the experiment (November,

28), the ponds were stocked with di¡erent propor-tions of carps, JN, and NT at a stocking density of5000 ¢ngerlings ha�1 (Table 1). The JN and NT werechosen to grow with the traditional carp polyculturebecause these species are preferred by consumersand because these three species comprise more than99% of the ¢sh produced in the region of study. Apolyculture using only the four carp species was con-sidered to be the control and is the most commonlyused in the region studied (IBAMA 2005).

Growth and yield

For weight determination, measurements and feedadjustment, samples of at least 10% of the ¢sh fromeach species were collected periodically (everymonth) using a pen net. The ¢sh were weighed, mea-sured and immediately returned to the water. The to-tal ¢shweight of each pondwas then estimated usingthemeanweight of the sampled ¢shmultiplied by thetotal number of ¢sh stocked initially. At the end of theexperiment, all ¢sh were harvested and the totalnumber, weight and size of each ¢sh species weredetermined. Survival rate (based only on ¢nal data)and yield datawere then calculated.The growth and yield indexes measured and/or

calculated were total biomass (g), mean body weightby species (g), daily weight gain (DWG5 fW� iW/t),standard length (cm), weight coe⁄cient of variation(WCV5SD/mean, %) and speci¢c growth rate[SGR5100. [Ln (fW)^Ln (iW)/t] in which fW is the¢nal weight, iW is the initial weight and t representdays of culture. Survival rate and food conversionwere also analyzed.

Feed and feeding regime

Because the experiment was carried out using ¢shspecies with di¡erent feeding habits, several types offeed were used. A single commercial type of extrudedfeed (£oating pellets with1^2mm, up to 60 days, and3^4mm from 60 days to the end of the experiment,with 42% crude protein and 3400 kcal kg�1 DE)was used to feed JNand NT. For grass carp, fresh dou-ble-minced camerun grass (Pennisetum purpureum)was o¡ered 1h before other food, at a rate of 50% of

GC biomass (wet weight); common carps were fedwith ground corn hydrated previously for1h.The fer-tilization regimen described above allowed thegrowth of phyto- and zooplankton, whichwere usedby the ¢ltering species. In the ¢rst month, all foodwere fed at a rate of 5% of total ¢sh biomass stocked;after that, ¢shwere fed three times a day (1000,1330,and 1700) with a rate of 4% of ¢sh biomass stockedper day during the second month and reduced to 2%from the third month onward. The feeding quantitywas adjusted at monthly intervals after estimatingthe biomass increase through samplings at monthlyintervals.The feed conversion ratio (FCR) is regularly esti-

mated for single species as the weight of feed added/increase in ¢sh biomass, but in the present study,where several species were reared together with ac-cess to natural food, the values for FCR were calcu-lated for the whole ¢sh community and consideringthe weight of all foods o¡ered (ground corn, mincedgrass, and extruded feed) as reviewed byAbdelghanyand Ahmad (2002), ignoring the natural foodconsumed by the ¢sh.

Climate conditions

Climate data such as atmospheric temperature andrainfall were obtained from the meteorological sta-tion at Empresa Brasileira de Pesquisa AgropecuaŁ ria(EMBRAPA) ^ Trigo, Passo Fundo, RS.

Water quality measurements

Water temperature and dissolved oxygen concentra-tionsweremeasured twice a day (0800 and1600) at adepth of 30 cm with oxygen meter (YSI model 550A,Yellow Spring Instruments,Yellow Springs, OH, USA).Simultaneously, pH (Bernauer pH meter), total am-monia N (colorimetric test) and water transparency(Secchi disc) were also measured. Total alkalinityand hardness were measured using colorimetrictests at two 2-week intervals.

Statistical analysis

The data obtained are presented as treatmentmeans � standard error of the mean (SEM) andwereanalysed using the InsTat Sigma statistical package.To compare two groups, the means of each groupwere compared using Student’s t test; to compare

Jundia and Nile tilapia increases carp polyculture performance L B da Silva et al. Aquaculture Research, 2008, 39, 542^551

r 2008 TheAuthors544 Journal Compilationr 2008 Blackwell Publishing Ltd, Aquaculture Research, 39, 542^551

three or more groups, the analysis of variance (ANOVA)for a completely randomized design, followed by Tu-key’s multiple range test at a 5% level of signi¢cance,was used.

Results

Climate conditions

The climate conditions in Passo Fundo city (281150S/521 240W, 687m above sea level) during the experi-ment are shown in Fig.1. Rainfallwas unusually lowerthan normal in December 2005 and in April andMay2006.

Water quality parameters

No di¡erence in water temperature was observedamong the 12 ponds in the experiment (Fig. 2). ThepH values ranged from 7.06 to 7.6 in the morningand from 7.47 to 8.3 in the afternoon (Fig.2).The Sec-chi disc water transparency ranged from 33.6 to65.3 cm in the morning and from 34.1 to 80.7 cm inthe afternoon (also with statistical di¡erences

between ponds). The water transparency measure-ments by the Secchi disc were divided into threeclasses (o30 cm, from 30.1 to 60 cm and 460 cm),and the distribution in each tank is shown in Fig.3.The alkalinity and total hardness values are

shown in Fig. 2. In all ponds, the alkalinity valuewas lower than the total hardness value. The totalammonia-N values were always under 0.6mg L�1 inall ponds. Total hardness varied from 26.25 to70.67mg CaCO3 L

�1.

Growth and yield

The ¢nal weight,WCV, DWG, SGR, survival rate, andyield are shown inTable 2.All species had similar initial weights but the ¢nal

weights among species, in the di¡erent treatments,were statistically di¡erent. Considering the mean ofthe treatments, the higher weight obtained for CCwas with treatment IV (T-IV), but the weight of theCC in treatment II (T-II) presented lower variability(Table 2) in the 162-d production cycle. Grass CarpfromT-IV showed a higher weight, but the most uni-formweightwas obtainedwithT-II.Treatment IValso

05

10152025303540

1 7 13 19 25 31 37 43 49 55 61 67 73 79 85 91 97 103

109

115

121

127

133

139

145

151

157

Days of experiment

Atm

osp

her

ic t

emp

erat

ure

(° C

)

28/11/2005 08/05/2006

05

101520253035404550

1 7 13 19 25 31 37 43 49 55 61 67 73 79 85 91 97 103

109

115

121

127

133

139

145

151

157

Days of Experiment

Rai

nfa

ll (m

m/d

ay)

28/11/2005 08/05/2006

MT mT medT(a)

(b)

Figure 1 Temperature and rainfall distribution during the experimental period. (a) Daily values of maximum tempera-ture (MT), minimum temperature (mT) and medium temperature (medT). (b) Daily values of rainfall (mm day�1). Day1corresponded to November 28th, 2005.

Aquaculture Research, 2008, 39, 542^551 Jundia and Nile tilapia increases carp polyculture performance L B da Silva et al.

r 2008 TheAuthorsJournal Compilationr 2008 Blackwell Publishing Ltd, Aquaculture Research, 39, 542^551 545

allowed a higher weight gain for SC, BC, and JN; inaddition, NT fromT-IVshowed a highermeanweight.The DWG also varied between the replicates of the

same treatment, characterizing the same pond e¡ect,but, for some species, they were extremely similaramong the four treatments. The higher DWG for JNwas found in T-IV (3.2 � 1.27 g day�1). For NT, theDWG obtained in treatment III (T-III) andT-IVwas si-milar. For SGR (% day�1), no statistical di¡erenceswere found between groups in each treatment andbetween di¡erent treatments.The survival rate in treatment (T-I), T-II, T-III,

and T-IV was 72.93 � 16.24%, 85.86 � 1.58%,63.82 � 10.82% and 68.50 � 16.53% respectively,and, except for T-II, were considered to be lower thanthe desired mean survival rate (7585%,Table 2). Re-garding the survival rate of each species, SC showeda low survival rate, ranging from only 21.38 � 9.35%to 35.75 � 8.80%.The survival rate of BC varied from

63.6 � 27.06% to 100%; CC, from 57.20 � 23.89% to96.67 � 3.34%; and GC, from 61 � 12.78% to86 � 3.61%. In treatments containing JN, the survi-val rate was lower than desired: 70 � 11.15% in T-IIand 76.53 � 21.52% inT-IV. A similar patternwas ob-served for NT: 80.2 � 4.03% survival in T-III and86.05 � 6.07% inT-IV.An important parameter to evaluate, besides the

¢nal yield and the ¢nal weight of each species, is thevariation in ¢shweight (Fre¤ chette 2005). Consideringthe WCV between treatments, the range was from10.6% inT-II to 38.8% inT-I.To demonstrate variability within the same spe-

cies, the ¢sh harvested were distributed into di¡erentweight classes (Fig.4). One important parameter alsoillustrated in the same ¢gure is the percentage of ¢shthat could reach marketable size in a single162-daysculture cycle. For CC, the ¢sh were divided in to fourweight classes and, in all replicates of all treatments,

(a)

10

15

20

25

30

T-I T-II T-III T-IV

Wat

er t

emp

erat

ure

(°C

)

(c)

6.46.66.8

77.27.47.67.8

88.2

T-I T-II T-III T-IV

pH

0

10

20

30

40

50

T-I T-II T-III T-IV

Alk

alin

ity

(mg

CaC

O

l )

(e)

0

2

4

6

8

10

12

T-I T-II T-III T-IV

Dis

solv

ed o

xyg

en(m

g l

) ***

*

(b)

020406080

100120140

T-I T-II T-III T-IV

Ele

tric

co

nd

uct

ivit

y(m

Osm

l )

(d)

0

10

20

30

40

50

60

T-I T-II T-III T-IV

To

tal h

ard

nes

s(m

g C

aCO

l

)

(f)

Figure 2 Mediumvalues ( � SEM) measured for water temperature (a, 1C), dissolved oxygen (b, mg L�1), pH (c), electricconductivity (d, mOsm L�1), alkalinity (e, mg CaCO3 L

�1) and total hardness (f, mg CaCO3 L�1) in the di¡erent experi-

mental ponds during all experiments. Asterisk indicates statistical di¡erence between the morning and afternoonmeasurements.

Jundia and Nile tilapia increases carp polyculture performance L B da Silva et al. Aquaculture Research, 2008, 39, 542^551

r 2008 TheAuthors546 Journal Compilationr 2008 Blackwell Publishing Ltd, Aquaculture Research, 39, 542^551

the ¢sh were always distributed in only two of theseclasses. T-II showed a higher percentage of market-able ¢sh and T-I showed the lower percentage of ¢shthat reached commercial weight. GC and SC showeda higher variation and none of these ¢sh reachedmarketable weight. Only in T-III and T-IV BC pre-sented a size ready for the market. In all replicates ofT-II andT-IV, JN presented marketable weight. All NTspecimens in all replicates weighted more than 300 gand reached marketable size.The calculated yield per hectare (Table 2) during

the 162 days of the experiment was highly variableamong replicates of the same treatment, which is re-£ected in the higher SEM in the treatments. In gener-al, regardless of the treatment, the total yield variedfrom 2083.33 � 183 to 2801.67 � 111.42 kgha.Feed conversion ratio (FCR,Table 2) varied from 2.2

to 3.2 kg of food per kilogram of ¢sh produced andshowed no di¡erence between treatments.

Discussion

Climate conditions

Climate conditions a¡ect water parameters. In thebeginning of the experiment, average temperatureswere higher and rainfall were much lower thanusually expected at this time of the year, whichmighthave had a positive e¡ect on water transparency(Fig. 3). In contrast, water transparency decreasedsigni¢cantly in April and May 2006, when rainfallwas above the expected range and, consequently,

there was a reduction plankton availability to ¢lter-ing ¢sh.

Water quality and survival rate

All parameters were found to be within acceptablevalues for water ponds used in ¢sh culture as re-ported by Boyd (1982), except for the dissolved oxy-gen (DO) levels measured in the morning, under5mg L�1in all replicates in all treatments. No signif-icant correlationwas found between species rate andthewater quality parameters.Themeanalkalinity le-vels were considered to be low, but not low enough toa¡ect the primary production of the pond (Boyd1982).The speci¢c survival rate percentages found in the

four treatments were lower than those found byother authors such as Jena, Ayyappan and Aravin-dakshan (2002), Jena, Ayyappan, Aravindakshan,Dash, Singh and Muduli (2002), Zoccarato, Benatti,Calvi and Bianchini (1995) and Abdelghany andAhmad (2002) and also lower than that we found inour previous work (Silva et al. 2006). The reasons forthe higher ¢sh mortality in this study might berelated to water quality, predation or due to the lowinitial weight and small stocking size.

Growth and yield

The most prominent result was the fact that, despitethemortality rates, a clear positive e¡ect onyield was

< 30 cm 30.1- 60 cm > 60 cm

0%

20%

40%

60%

80%

100%

Pond 1,II/2

Pond 2,III/1

Pond 3,IV/2

Pond 4,II/1

Pond 5IV/3

Pond 6,III/3

Pond 7,I/3

Pond 8,II/3

Pond 9,I/1

Pond10, IV/1

Pond11, III/2

Pond12, I/2

Treatments / replicates

Sec

chi-D

isk

Tra

nspa

renc

y D

istr

ibut

ion

Figure 3 Water transparency of all ponds was measured daily using a Secchi disc and classi¢ed in to three classes(o30 cm; between 30.1and 60 cm; and460 cm).The data are shownas percentual of days inwhichwater transparencyfell in each class.

Aquaculture Research, 2008, 39, 542^551 Jundia and Nile tilapia increases carp polyculture performance L B da Silva et al.

r 2008 TheAuthorsJournal Compilationr 2008 Blackwell Publishing Ltd, Aquaculture Research, 39, 542^551 547

achieved by the introduction of JN and/or NT. In thecase of NT, production (due to a higher survival rate)was higher than that of SC and BC. Another possiblereason for this increase in the productivityof polycul-ture with JN and/or NT (especially concerning iso-lated inclusion of JN) is given by Rahman et al.(2006), who postulated that the presence of arti¢cialfeed bene¢ts the pond in twoways: it is either directly

eaten by cultured animal or it indirectly supplies nu-trients through decomposition by bacteria, fungi andprotozoa.These authors showed that only 21% of thenitrogen and 19% of the phosphorus in the arti¢cialfeed are retained by the ¢sh.The remaining nutrientsare used by the phytoplankton; this stimulates theproliferation of bacteria, fungi and protozoa, whichare consumed by the zooplankton. This increase in

Table 2 Final weight, weight coe⁄cient of variation, daily weight gain, speci¢c growth rate (SGR), survival rate, yield andfeed conversion rate (FCR) of di¡erent treatments for common carp (CC), grass carp (GC), silver carp (SC), bighead carp (BC),jundia (JN) and Nile tilapia (NT)

Sp.

Treatment

I II III IV

Final weight (g) CC 1137.75 � 98.72B� 1285.92 � 39.35AB 1385.54 � 49.57A 1536.25 � 62.03A

GC 441.1 � 34.22B 407.3 � 14.13B 525.1 � 36.34AB 573.8 � 42.09A

SC 366.8 � 28.32B 337.9 � 22.95B 554 � 74.55A 632.3 � 32.85A

BC 582.2 � 25.1B 544.9 � 20.97AB 890.7 � 37.61A 1245.5 � 228.25A

JN – 316.1 � 6.37 – 352.7 � 12.55

NT – – 663.8 � 16.00 733.7 � 52.92

Weight coefficient of variation (%) CC 38.8 10.6 18.24 11.41

GC 39.56 16.98 35.28 37.39

SC 27.83 17.37 30.09 13.74

BC 15.54 12.16 11.17 36.65

JN – 15.05 – 25.65

NT – – 17.47 26

Daily weight gain (g day� 1) CC 7.9 � 2.14 7.9 � 0.39 8.4 � 1.04 8 � 1.56

GC 2.6 � 0.69 2.5 � 0.17 3.1 � 0.75 3.1 � 0.58

SC 2.2 � 0.40 2.1 � 0.12 3.4 � 0.58 4.6 � 1.04

BC 3.5 � 0.29 3.4 � 0.17 5.5 � 0.38 5.7 � 2.02

JN 1.9 � 0.09 3.2 � 1.27

NT 4 � 0.35 4.2 � 0.52

SGR (% day� 1) CC 2 � 0.06 2 2 � 0.03 2 � 0.04

GC 1.4 � 0.06 1.4 � 0.03 1.5 � 0.06 1.5 � 0.06

SC 1.7 � 0.06 1.7 1.8 � 0.06 1.8 � 0.06

BC 1.9 � 0.06 1.8 � 0.06 2 2 � 0.03

JN 1.4 � 0.03 1.5 � 0.03

NT 1.6 � 0.03 1.7 � 0.03

Survival rate (%) CC 57.20 � 23.89 96.67 � 3.34 64.80 � 13.22 66.67 � 33.37

GC 80.60 � 8.33 86.00 � 3.61 61.00 � 12.78 66.60 � 19.87

SC 35.75 � 8.80 24.44 � 4.45 28.68 � 2.02 21.38 � 9.35

BC 90.27 � 9.74 100.00 63.60 � 27.06 67.06 � 13.15

JN – 70.00 � 11.15 – 76.53 � 21.52

NT – – 80.20 � 4.03 86.05 � 6.07

Total 72.93 � 16.24 85.86 � 1.58 63.82 � 10.82 68.50 � 16.53

Yield (kg ha�1) CC 988.33 � 289.95 1170 � 30.04 1590 � 194.22 1437 � 165.54

GC 578.3 � 119.19 618.3 � 98.44 520 � 32.54 590 � 59.31

SC 351.7 � 60.23 421.7 � 59.56 145 � 61.16 156.7 � 21.33

BC 165 � 27.57 98.3 � 13.64 105 � 5.03 86.7 � 39.48

JN – 168.3 � 27.75 – 191.7 � 50.58

NT – – 441.7 � 117.11 523.3 � 168.32

Total 2083.33 � 183.00 2476.67 � 139.88 2801.67 � 111.42 2506.67 � 422.31

Total (kg ha�1 year�1) 4693.93 � 412.32 5580.14 � 315.16 6312.4 � 251.05 5647.74 � 951.49

FCR (%) 3.2 � 1.8 2.2 � 1.2 3.1 � 1.8 2.9 � 1.6

�Di¡erent capital letters after the means indicate signi¢cant di¡erences between treatments means (ANOVA, Tukey or Student’s t test,Po0.05).

Jundia and Nile tilapia increases carp polyculture performance L B da Silva et al. Aquaculture Research, 2008, 39, 542^551

r 2008 TheAuthors548 Journal Compilationr 2008 Blackwell Publishing Ltd, Aquaculture Research, 39, 542^551

plankton availability bene¢ts ¢ltering species (SC, BCand NT).High percentages of CC may a¡ect the pond nega-

tively, by increasing turbidity and reducing photo-synthesis and primary production. Thus, theintroduction of JN (T-II) with the simultaneous re-duction of CC had a positive e¡ect on plankton avail-ability (Silva et al. 2006). However, total CC exclusionof CC is not recommended (Silva et al. 2006) in thatbrowsing and burrowing for food by CC helps to re-lease the nutrients from the bottom of the water col-umn and these nutrients stimulate photosynthesisand increase the phytoplankton and zooplanktonbiomass (Rahman et al. 2006).The introduction of JN had no e¡ect on other spe-

cies because JN is an omnivorous species (Gomeset al. 2000). Jundia feeds well on arti¢cial food andcorn grains and might compete for food with NTand CC; however, no negative e¡ect was observed inthese species with JN introduction. The growth per-formance of JN in this work was better than that re-ported previously (Barcellos, Kreutz, Quevedo,Fioreze, Soso, Cericato, Fagundes, Conrad, Baldissera,Bruschi & Ritter 2004; Souza, Pouey, Camargo & Vaz2005), including in polyculture (Silva et al. 2006).

In T-IV, the mean NT yield was higher than thatfound in T-III, probably because inT-IV the mortalityrate of CC was higher and, thus, there was no compe-tition for arti¢cial food with NT. Lutz (2003) reportedthat the overlapping food preferences of the speciesmay be a problem in polycultures. Moreover, CCachieved the best performance in the presence ofNT. Papoutsoglou, Petropoulos and Barbieri (1991)also observed that CC and NTachieved better resultswhen cultured together than when cultivated in amonoculture system. In polyculture systems, only aproper combination of ecologically di¡erent species,at adequate densities, will utilize the availableresources e⁄ciently because of the maximization ofsynergistic ¢sh^¢sh relationships and minimizationof antagonistic ones (Silva et al. 2006).As expected, all species showed lower SGR in a

162-days cycle when compared with the 86-dayscycle (Silva et al. 2006). However, this might beexplained by the fact that younger ¢sh grow faster,giving a sigmoid-shaped growth curve.The total yield varied from 2083.33 � 183 to

2801.67 � 111.42 kg ha�1 similar to the yieldobtained by Jena , Ayyappan, Aravindakshan, Dashet al. (2002) for polyculture of Indian and Chinese

Figure 4 Percentual distribution of harvested ¢sh in di¡erent weight classes in each treatment. The number above eachcolumn indicates the percentual of ¢sh that could reach the marketable size.

Aquaculture Research, 2008, 39, 542^551 Jundia and Nile tilapia increases carp polyculture performance L B da Silva et al.

r 2008 TheAuthorsJournal Compilationr 2008 Blackwell Publishing Ltd, Aquaculture Research, 39, 542^551 549

carps.Whenanalysed in terms of growth parameters,the most promising ratio was obtained with T-III,probably due to the high production obtained withNT that compensated for the excluded SC and BC.The negative e¡ect of a high stocking rate of CC

was not observed when NT was introduced in isola-tion (T-III), probablydue to the excellent performanceof NT in this experiment. Taken together, the highyield of NT, the positive e¡ect of its introduction andthe high mortality of ¢ltering carps (especially SC)clearly suggest that the percentage of substitution ofSC and BC by NT may increase and/or the stockingrate may decrease.The FCR calculated in this work was higher than

that found by Abdelghany and Ahmad (2002), whoreported an FCR of 0.461.37 kg. However, in a carppolyculture analysed by Jena , Ayyappan, Aravindak-shan (2002), FCR varied from1.47 to 3.16 kg, similarto the values reported herein.

Conclusion

Based on the data presented in this study, the intro-duction of JN and/or NT had a positive e¡ect on allgrowth parameters when compared with carp-onlypolyculture.The reduction in common carp ratio alsohad a positive e¡ect on all growth and yield para-meters. In addition, despite the low survival rates,productivity in all treatments was much higher thanthe mean productivity levels in Rio Grande do Sulstate. At this stage, more studies are necessary to de-termine the ideal substitution percentages and stock-ing densities, especially of the ¢ltering carps by NT.

Acknowledgments

This work was supported by grants from FAPERGS-PROCOREDES 04/0541-6 (Fundac� a� o de Amparo aPesquisa do Estado do Rio Grande do Sul), SCI-EM-BRAPA PRODETAB 0149/2001/2 (Secretaria deCooperac� a� o Internacional, Empresa Brasileira dePesquisa AgropecuaŁ ria) and Universidade de PassoFundo (UPF). All academics have scienti¢c innitia-tion fellowships (Jovani A Finco, FAPERGS; Filipe Rit-ter, CNPq; Alexandra Bedin, PIBIC-UPF). LeonardoBolognesi da Silva is an M.Sc student and has aCAPES fellowship. The authors are indebted to PauloNadal and Dirceu de Andrade for all the assistancewith the pond management and for maintenance ofthe best laboratory conditions, and to Mauro Rizzar-di,Vilson Klein,Vanderli Rossatto, and Claudiomir de

Lima for the friendly support at CEPAGRO ^University of Passo Fundo.

References

Abdelghany A.E. & Ahmad M.H. (2002) E¡ects of feedingrates on growth and production of Nile tilapia, commoncarp and silver carp polycultured in fertilized ponds.Aquaculture Research 33, 415^423.

Barcellos L.J.G., Kreutz L.C., Quevedo R.M., Fioreze I., SosoA.B., Cericato L., Fagundes M., Conrad J., Baldissera R.,Bruschi A. & Ritter F. (2004) Nursery rearing of jundia,Rhamdia quelen (Quoy & Gaimard) in cages: cage type,stocking density and stress response to con¢nement.Aquaculture 232,383^394.

Bhakta J.N., Sarkar D., Jana S. & Jana B.B. (2004) Optimizingfertilizer dose for rearing stage production of carp underpolyculture. Aquaculture 239,1235^1239.

Boyd C.E. (1982) Water Quality Management for PondFish Culture. Elsevier Scienti¢c Publishing, New York,USA.

Fre¤ chette M. (2005) A comment on the methodology ofstocking experiments. Aquaculture 250, 291^299.

Gomes L.C., Golombieski J., Chippari-Gomes A.R. & Baldis-serotto B. (2000) Biologia do jundia Rhamdia quelen(Teleostei, Pimelodidae). CieΠncia Rural 30,179^185.

Instituto Brasileiro doMeioAmbiente e dos Recursos Natur-ais RenovaŁ veis ^ Ibama. Diretoria de Fauna e RecursosPesqueiros. Estat|¤ stica da Pesca (2005). http://www.presidencia.gov.br/estrutura_presidencia/seap/estatistica/

Jena J.K., Ayyappan S. & Aravindakshan P.K. (2002) Com-parative evaluation of production performance in variedcropping patterns of carp polyculture systems.Aquaculture 207, 49^64.

Jena J.K., Ayyappan S., Aravindakshan P.K., Dash B., SinghS.K. & Muduli H.K. (2002) Evaluation of production per-formance in carp polyculture with di¡erent stocking den-sities and species combinations. Journal of AppliedIchthyology18,165^171.

Kestmont P. (1995) Di¡erent systems of carp production andtheir impacts on the environment. Aquaculture 129,347^372.

Lutz G.C. (2003) Polyculture: principles, practices, problems,and promisse. Aquacultural Magazine, March/April.

Papoutsoglou S.E., Petropoulos G. & Barbieri R. (1991) Poly-culture rearing of Cyprinus carpio (L.) and Oreochromisniloticus using a closed circulated system. Aquaculture103,311^320.

Rahman M.M., Verdegem M.C.J., Nagelkerke L.A.J., WahabM.A., Milstein A. & Verreth J.A.J. (2006) Growth, produc-tionand food preference of rohu Labeo rohita (H.) inmono-culture and in polyculture with common carp Cyrpinuscarpio (L.) under fed and non-fed ponds. Aquaculture 257,359^372.

Jundia and Nile tilapia increases carp polyculture performance L B da Silva et al. Aquaculture Research, 2008, 39, 542^551

r 2008 TheAuthors550 Journal Compilationr 2008 Blackwell Publishing Ltd, Aquaculture Research, 39, 542^551

Silva L.B., Barcellos L.J.G., Quevedo R.M., Souza S.M.G.,Kreutz L.C., Ritter F., Finco J.A. & Bedin A.C. (2006) Alter-native species for traditional carp polyculture in southernSouth America: initial growing period. Aquaculture 255,417^428.

Souza L.S., Pouey J.L.O.F., Camargo S.O. & Vaz B.S.(2005) Crescimento e sobreviveŒ ncia do cat¢sh de canal

(Ictalurus puntactus) e jundia (Rhamdia sp) no outono-inverno do Rio Grande do Sul. CieΠncia Rural 35,891^896.

Zoccarato I., Benatti G., Calvi S.L. & Bianchini M.L. (1995)Use of pig manure as fertilizer with or without supple-ment feed in pond carp production in Northern Italy.Aquaculture129,387^390.

Aquaculture Research, 2008, 39, 542^551 Jundia and Nile tilapia increases carp polyculture performance L B da Silva et al.

r 2008 TheAuthorsJournal Compilationr 2008 Blackwell Publishing Ltd, Aquaculture Research, 39, 542^551 551