La longueur totale, la formation et le rayon des écailles ont été examinés. Les écailles commencent à se former pour une longeur totale de 13 mm, et sont formées pour une longueur du poisson de 17 mm. La relation entre taille du poisson et rayon de l'écaille est curvilinéaire pendant la phase juvénile de #P. lineatus$. (Résumé d'auteur

Campana, M.

Cordiviola de Yuan, E.

Horizon / Pleins textes

Scale development of Prochilodus lineatus 
( Val.) (Pisces, Curimatidae) 
juveniles from the Parana River 
E. CORDIVIOLA DE YUAN and Mirta CA~WPANA (1) 
ABSTRACT 
Tofal body length and scale radius as me11 as the squamation of Young Proc,hilodus lineatus mere examined. Fish 
began to form squamation af 13 mm and were completely scaled at 17 mm total length. The relationship between body 
length and scale size is curvilinear during the early life of the fish. 
KEYWORDS : Scale - Juveniles - Prochilodus lineatus - Curimatidae - Parana River - Argentina. 
DESARROLLO DE LA ESCA~~A EN JUVENILES DE PROCHILODUS LINEATUS (VOL.) (PISCES, CURI~~ATIDAE) 
DEL Ri0 PARANA 
Se analiza la relacion largo total del pez-radio de la escama asi como su escamarion. Los resultados muestran que 
esta empieza a 10s 13 mm, cubriéndose todo’el cuerpo a 10s 17 mm de longitud total. La relation entre la longitud del 
cuerpo y el tamano de la ekama es curvilinea durante 10s primeros estadios del pez. 
PALABRAS CLAYES : Escama - Juveniles - Prochilodus lineatus - Cbrimat,idae - Rio Parank - Argentina. 
RÉsuarE 
LE DÉVELOPPEMENT DES ÉCAILLES DES JUVÉNILES DE PROCHILODUS LINEATLW (VAL.) (PISCES, CURWATIDAE) 
DU FLEUVE PARANA 
La longueur tofale, la formation ef le rayon des écailles ont été examinés. Les écailles commencenf à se former 
pour une longueur totale de 13 mm, et sont formées pour une longueur du poisson de 17 mm. La relation entre taille 
du poisson et rayon de l’écaille est curvilinéaire pendant la phase juvénile de P. lineatus. 
MOTS CLES : Écaille - Juvéniles - Prochilodus lineatus - Curimat,idae - Paran& - Argentine. 
(1) Instituto national de limnologia (Inali-Conicei), Macia 1933 - 3016 Santa Tome (Santa Fe), Argentina. 
Reu. Hydrobiol. trop. 26 (4) : 327-332 (1993). 
328 E. CORDIVIOLA DE YUAN, M. CAMPANA 
FIG. 1. - St*udy area. 1: Los Sapos Island and Salado River, and 2: Lagoon of El Espinillar Island. 
La zone d’étude. 1 : île Los Sapos et rivière Salado; 2 : lac de l’île El Espinillar. 
INTRODUCTION 
The Paran& River is one of the more important 
rivers in South America. It flows for about 2,000 km 
through Argentina draining 33,000 km2 and ending in 
an important alluvial plain 1,100 km long. It is for- 
med by a very complex system of islands, tributaries, 
branches and lagoons, a11 related in different degrees 
with the principal channel (LOWE-MCCONNE~L, 1987 ; 
CAROZZA and CORDIVIOLA DE YUAN, 1991). In this 
fluvial macrosyst.em (NEIFF, 1990) there are more 
than 300 fish species, being the ‘L sabalo ” (Prochilodus 
lineatus) (Val.) dominant both in number and in bio- 
mass (BONETTO et al., 1969, 1970 and 1971; CORDI- 
VIOLADE YUAN, 1974a and1992; OLDANI and OLIVE- 
ROS, 1984). 
The “ sabalo ” inhabits lentic as well as lotit 
waters of t.he system. Adults spawn in the river in 
summer when water levels are high. Later t.he larvae 
and juveniles grow in small lagoons near the lot,ic 
environments where they cari find shelter and food 
(CORDIVIOLA DE YUAN, 1974a). 
P. lineatus adults transforms organic matter since 
its diet. is composed more of detritus than micro- 
organisms (BOWEN el al., 1954). A series of morpholo- 
gical t,ransformations of the digest.ive tract occurs 
during the post-larval and juvenile stages which COT- 
respond with c.hanges in their diet: from zooplankton 
to phytoplankton to detritus (WELCOMME, 1985; 
ROSSI, 1992). BAYO and CORDIVIOLA DE YUAN 
(1992 a and b) who studied the fatty acids as indica- 
t,ors of the species assimilation obtained similar 
result,s. 
Previous investigation on P. lineatus age and 
growth were conducted in fishes from different envi- 
ronments of the Parana River (CORDIVIOLA DE 
YUAN, 1971 and 1974b; CAROZZA and CORDIVIOLA 
DE YUAN, op. cif.). Most of these studies were concer- 
ned with fish older than 2 years old, in which the age 
was det,ermined by lepidological method. Very little 
is known about, larvae and juvenile growth and squa- 
mation. 
The present study has been undertaken in order to 
investigate the early scale development of P. lineafus 
by analyzing the relationship between total length 
.and scale radius as well as early squamation of juve- 
nile fish. 
RESEARCH SITES 
Fish were caught in two areas : a) Near t.he mouth 
of the Salado River ‘in the Coronda River (tributary 
of the Parana) in t,he alluvial plain of the Parana. 
They were obtained in the Salado River as well as in 
the lagoons of the Los Sapos Island (31” 40’ S; 
60” 43’ W) the later environments are shallow and 
small, and b) in a permanent lagoon (31” 42’ S; 
60” 37’ W) located in El Espinillar Island in the allu- 
vial plain near the Colastiné River and the principal 
channel of the Parana (fig. 1). 
It was not possible to obtain fish of a wide range of 
sizes in a11 the environments of t.he alluvial plain at 
the same time. For t.his reason samples were t.aken 
during 1988 in February, March, April, October, and 
December, and along 1989 in March, April, and 
August. 
Reu. Hyhobiol. trop. 26 (4) : 327-332 (1993). 
DEVELOPMENT OF PROCHILODUS LINEATUS FROM THE PARANA RIVER 329 
a 
AM 
Sr 
PM 
b 
FIG. 2. - a) Scale sampling area on the fish. b) Prochilodus 
lineatus scale indicating the radius Sr (38” to the anterior- 
posterior axis A) where measurements where taken ; C: circulii ; 
AM: anterior margin; PM: posterior margin; R: radius 
(adapted from CORDIVIOLA DE YUAN, 1971). 
a) Zone de prélèvement d’écailles; b) Écaille de Prochilodus 
lineatus auec l’axe Sr (à 38” de l’axe antéro-posférieur) sur lequel 
les mesures ont été faites. Les autres symboles indiquent les 
circuli (C), les faces antérieure (AM) et postérieure (PM) et les 
rayons (R) (d’après CORDIVIOLA DE YUAN, 1971). 
MATERIAL AND METHODS 
The total length of 329 fishes ranged from 8.0 
(post-larvae) to 235 mm and weight from 0.01 to 
212 g, 86 fishes were subsampled for the squamation 
study. 
Standard, forlr and total lengths, weight, and scale 
samples were obtained from the remaining 243 fish 
prior to preservation in 10 y0 formalin. Scales 
(N = 10) were taken from t.he left side of the body 
5 from the row immediately above t,he lateral line 
and behind a vertical that passes through the origin 
of the dorsal fin and the ot,her five scales from the 
second row (CORDIVIOLA DE YUAN, 1971) (fig. 2a). 
Scale samples were cleaned and mounted between 
t,wo slides. They were viewed in a Shadowgraph 
Nikon with 50 and 20 X magnification. For each fish 
the scale radius was measured on a straight line that 
forms an angle of 38” wit.h its anterior-posterior axis 
taking as its vertex the scale tenter (CORDIVIOLA DE 
YUAN, op. cif.) (fig. 2 b). 
The relationship between total length (Tl) and 
scale radius (Sr) was estimated as follows: 
Sr = d+e Tl+f(T1)2 
where: Tl = total length in mm, Sr = scale radius 
in mm; 
d, e and f are constants estimated by a least squares 
adjustment. 
TO provide a simple and continous way of quanti- 
fying the relative growt.h of the scale at any body 
size it was calculated the relationship lg-lg and from 
it the first derivative (CASSELMAN, 1990). 
In some fish the caudal fin was damaged, and it 
was impossible to obtain accurate measurements of 
total length. In such cases, the tot.al length was esti- 
mated based on a regression relationship between 
total and standard length, as follow: 
Tl = 0.29 + 1.21 Sl R2 = 0.99 
The length-weight. relationship calculated from 
the data registered was: 
W = 0.01 T13J6 R2 = 0.99 
TO examine early squamation fishes were washed 
with distilled water, placed in a solution of 1 y0 
KOH, treated with alizarin red to stain the scales, 
and finally examined with an Olympus stereoscopic 
binocular mic.roscope. Drawings were made showing 
the distribution of scales on the body at different 
sizes. 
RESULTS 
The scale-body relationship calculated was (fig. 3, 
and table 1) : 
Sr = 0.103 + 0.039 Tl + 0.0001 T12 R2 = 0.98 
The estimated regression log-log, was: 
Log Sr = - 0.618 - 0.800 Log Tl + 0.586 (Log T1)2 
R2 = 0.97 
From this equation was calculated the first deriva- 
tive (fig. 3). 
For P. lineatus juveniles of the Parana River the 
scale grew at a slower rate than the body up t,o 
Rev. Hydrobiol. trop. 26 (4) : 327-332 (199,3). 
E. CORDIVIOLA DE YUAN, M. CAMPANA 
Prochilodus lineatus 
(ParanS River ) 
8 - 1.0 -- --------isometry------ 
. -If ‘ts 
OI’ , , , , , , , 
0 80 160 240 
Total length (mm) 
FIG. 3. - Upper panel: scale radius-body length relationship 
for 243 “ sahalo ” Prochilodus [inealus (8-235 mm Tl) from 
several water bodies of the alluvial plain of the Parana River. 
Coefficients and st,atistics for the arithmetic relat.ionship are 
given in t,ahle 1. Lower panel: relative growt,h is indiçated by 
t.he rrlation bet.ween the first derivative of the Log-log relation 
(hase 10) and body length. Coefficients of the first derivat,ive 
and st.atistics for the Log-log relat.ion are given in table 1. 
Hrlation entre lu longueur totale de Prochilodus lineat.us 
(243 operimrns de taille comprise entre 8 et 325 mm) provenant de 
divers plans d’eau de la plaine alluviale du Parand avec en haut le 
rayon de 1’4caille. en bas la croissance relative calculée par la 
dérivée de la relation Log-log (base 10). Voir le tableau I pour les 
données numériques. 
TABLE 1 
Mode1 At.ting results for the relationship between total length 
and scale radius of Prochilodus linrafns juveniles from 
Parana River 
Déferminaiion des coefficients des relations enfre longueur totale ei 
rayon de l’écaille pour les juvéniles de P. lineatus 
du f[euve Parami 
Arithmetic relation 
estimate stnd. error ratio 
Coeff. 1 0.103 0.039 2.658 
Coeff. 2 3.86 x 10v3 9.32 x 104 4.143 
Coeff. 3 8.84 x 105 4.04 x 10A 21.889 
Log-log relation 
estimate slnd. errer ratio 
Coeff. 1 -0.618 0.204 -3.034 
Coeff. 2 -0.800 0.224 -3.570 
Coeff. 3 0.586 0.061 9.611 
d 
FIG. 4. - Development of squamation on P. lineafus from the 
Parana River. a) 8-11 mm: body naked, b) 12-13 mm: the first 
scales appear, c) 14-15 mm: t.he scales are extended t.oward the 
posterior region, and d) 16-17 mm : body complet.ely scaled. 
Apparition des écailles chez P. lineatus du Parami. a) S-11 mm, 
le corps est nu; b) 12-13 mm, les premières écailles apparaissent; 
c) 1415 mm, les écailles se dtkeloppent dans la partie 
postérieure; d) 16-17 mm, le corps est recouvert d’écailles. 
Heu. Hydrobiol. frop. 26 (4) : .X7-,332 (1993). 
DEVELOPMENT OF PROCHILODUS LINEATUS FROM THE PARANA RIVER 331 
35 mm Tl, the range over which scale was isometric 
(fig. 3, lower panel). On larger fish the sc.ale grew at a 
faster rate than the body (up to reach K = 2.0 at 
240 mm Tl), changing from negative to positive allo- 
metry. 
The body is completely naked at 11 mm. At 12- 
13 mm scales start to appear in the anterior region of 
the body near the lateral line. The squamation 
spreads from this primary sit,e in the middle region 
of the body at 14-15 mm. The scales extend finally 
over the posterior region completely covering the 
body at 17 mm (fig. 4). 
DISCUSSION AND CONCLUSIONS 
In t.his work it is proved t,hat the relationship be- 
tween body length and scale is net linear during the 
early life of the fish. CAROZZA and CORDIVIOLA DE 
YUAN (op. cif.), grossly overstimated (in a linear 
regression) the time of scale formation of the fish 
(155 and 222 mm for females and males, respec- 
tively). The present study provides a more accurate 
estimation of early growth of P. lineatus. Combining. 
these data (i.e., from old and Young fish) wotild pro- 
vide a better estimation of overall growth. 
Fish squamation has been studied for more than 
80 species a11 over the world, most of them fresh- 
water ones species of t,he orders Anguiliformes, Clu- 
peiformes, Cypriniformes, Siluriformes, Salmoni- 
formes, Gasteroteiformes, Cypronodontiformes, 
Scorpaeniformes, Perciformes, and Pleuronect.i- 
formes (SIRE and ARNULF, 1990). The squamation 
.research aims have ranged, from age and growth stu- 
dies t.o systemat,ic analysis, and, others to determine 
the factors that might mitiate and organize the pro- 
cess in fishes. Among t,eleosts, seven different regions 
of first. scale appearance have been delimitated on 
t.he body. Some specie have only one sit,e, whereas 
others have t.wo or more. P. lineatus is in t.he first. 
group, with the localizat.ion in the anterior region of 
the body near the lateral line. 
Squamation data for South American fishes are 
scarce : ARAUJO-LIMA (1955) studied larval develop- 
ment of the amazonian Semaprochilodus insignis and 
analyzed scale appearance. GERY (1977) considers 
this genus to be only a subgenus of Prochilodus. 
Observations made on P. lineatus have de.mon- 
strated t,hat there is no evidence of scales in samples 
smaller than 12 mm t.otal length. The first scales 
appear in fîsh of 13 mm tot,al length, coinciding with 
the values obt.ained in a species of a similar genus : 
Semaprochilodus insignis, where scales appeared at 
13 mm (ARAU.JO-LIMA, op. cit.). 
The scale grows at. a slower rate than the tot.al 
length of the fish up to 35 mm, the size in which is 
isometric. From this point t,he scale grows at a faster 
rate than the total length. 
ACKNOWLEDGMENTS 
This work was financed through a grant from t,he National 
Council 8f Technical and Scient.ific Research of the Argentine 
Republic (PID NU 3-093800/88). Thanks to Pr. Liliana Rossi 
for the material, to the referees, specially Dr. John M. Cassel- 
man for his valuable observations. TO Lit. Luis Kieffer for the 
st.atistical and comput.er assistance and to Lionel Mchaudy. 
Manuscrit accepth par le Comité de rédaction le 10 nooernbre 1994. 
R~U. Hydrobiol. hop. 26 (4) : 327-3<32 (1993). 
332 E. CORDIVIOLA DE YUAN, M. CAMPANA 
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Heu. Hydrobiol. trop. 26 (4) : 327-332 (1993). 


Scale of development of Prochilodus lineatus (Val.) (Pisces, Curimatidade) juveniles from the Parana river

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