Biologia do saguirú (Characidae, Curimatinae)

Abstract

<abstract language="eng">In Brazil all the fishes belonging to the sub-family Curimatinae are called « saguirú ». The present work gives a biological study of the Curimatus elegans Steind., a small fish without any economical importance, which is to be found along the whole brazilian coast, down till Paraguay. The specimens utilized for the present study come from Fortaleza (Ceará, north-eastern Brazil). The C. elegans is « ilyophagus », that means, it feeds itself exclusively with those organic materials to be found in mud, specially with microscopical algae. The intestines are very extent, some of them measuring about 9 to 11 times body's length. Studies have been made about growth and age of the C. elegans; the biggest sizes found were of 153 mm. for females and 88 mm. for males. The C. elegans shows developed sexual glands during a long period (April to September). The movements of the spermatozoa, in contact with water is of 40 to 50 seconds of intense movements, ceasing after 70 to 100 seconds. In contact with 0.5% NaCl-solution spermatozoa show a big increase in movements-time, that can last till about 25 minutes. The eggs' diameter measures 0.70 to 0.73 mm., mature and hydrated it attains 0.93 to 1,00 mm. There is a certain correlation between the size of the body and the quantity of eggs. Big specimens can produce a total of 200.000 eggs. The average quantity contained in 1 gr. and 1 cc. is 6018 and 6229 eggs, respectively. Maturity and spawning in laboratory has been obtained due to injections of suspension of fish-hypophysis. Three or four hours after the injection, fishes show more movement and evident signs of excitation, proceeding spawning after 5 to 6 hours. Males, persecuting females, describe successive circles (merry-go-round) - carroussel), swimming side by side with females up to water's surface, where sexual products are start beating dry, for there is no blood yet. Circulation-scheme is to be found on fig. 4 and 5. The swim-bladder and the stomach are but delineated; the intestine is formed by a cylindric tube, all closed. At the place, where later on there will open the mouth, we find a group of ciliary hairs that produce a liquid current, very evident by the semi-circle formed by attached solid particles. After 36 hours, opening of the mouth and formation of the gill slits begin. At the age of 90 hours (4 mm.) the larvas swim well and start to feed themselves; the digestive tube is now all open and the swimbladder works already. During the first days of life, larvas have an adhesive organ situated at their frontal region (fig. 7) in form of a crescent, by means of which they hang to surrounding vegetation (fig. 6). When the larva begins to swim and to feed itself and its yolk are having been absorbed. the adhesive organ retracts and disappears. While larvas and alevins feed themselves with plancton, they have small eye-teeth, which disappear,. when fishes become « ilyophagus ». There exist too, during their life as larvas, pharyngeal-teeth. The lateral line appears in the larva after 16 t...

Reproductive aspects of Cyphocharax voga (Hensel) from Custódias Lagoon, Rio Grande do Sul, Brazil (Characiformes, Curimatidae)

“…The Curimatidae species seems to have a long reprOductive period as a characteristic, since the same results have been found by other authors (AZEVEDO et al 1938;MORAES et al 1984;ROMAGOSA et al 1984;CARVALHO 1984;HARTZ & BARBIERI 1994). The absolute fecundity (F), defined as the number of ovocytes that can be eliminated by female during a stage of posture, presented a mean value of 36608 oocytes, with values ranging from a minimum of 12519 to a maximum 56040.…”

“…Studies of the reproduction of some species ofCurimatidae can be found in AZEVEDO et al (1938), NOMURA & TAVElRA (1979), NOMURA & HAYASHI (1980), TAPHORN & LILYSTRON (1983), CARVALHO (1984), MORAES et al (1984) and ROMAGOSA et al (1984). It must be pointed out the works on C. voga carried out by HARTZ & BARBIERI (1994) and in isolated lagoons of Rio Grande do SuI.…”

A phylogenetic study of the neotropical characiform family Curimatidae (Pisces : Ostariophysi)

“…observ.). The utilization of that food source by at least some curimatids is also indicated by the food item studies of various authors (Azevedo et al, 1938;de Godoy, 1975;Nomura and Hayashi, 1980;Nomura and Taveira, 1979). Thus Reid's hypothesis of a particleprecipitating mucus system in some Old World Ostariophysan groups is apparently also applicable to the Curimatidae, paralleling the system used by some microphytophagous cichlid fishes (Moriarty et al, 1973) and some anuran tadpoles (Wasserzug, 1972).…”

Influência do ambiente no conteúdo calórico e na condição fisiológica de duas espécies migradoras de peixes neotropicais

“…Alimenta-se de lodo, algas, perifiton e detritos orgânicos, sendo considerada espécie de regime alimentar especializado, do tipo iliófago (Azevedo & Vieira, 1938;Leite et al, 1988;Fugi & Hahn, 1991).…”