Este estudo foi conduzido com o objetivo de obter a reprodução da pirapitinga-do-sul, Brycon opalinus, por intermédio da aplicação de hormônios indutores e determinar a distribuição de freqüência dos diâmetros dos ovócitos em fêmeas aptas à indução. Cento e vinte reprodutores apresentando comprimento entre 25,5 e 32,0 cm foram mantidos em um tanque circular de alvenaria, de 10 m de diâmetro, na Estação de Aqüicultura de Paraibuna/CESP. Para determinação das fêmeas aptas à reprodução, retiraram-se amostras de ovócitos com cateter plástico introduzido pela abertura urogenital. Estes ovócitos foram analisados quanto à cor, tamanho, posição da vesícula germinativa (núcleo) e distribuição de freqüência porcentual dos diâmetros. Os machos foram selecionados pela qualidade do sêmen. Vinte e nove fêmeas aptas à reprodução receberam duas injeções intramusculares de EPS (extrato de pituitária de salmão), sendo a 1ª, na dose de 5 mg/kg e a 2ª, de 10 mg/kg, com intervalo de 12 horas. Os machos que apresentavam ao redor de 90% de motilidade espermática e 85% de espermatozóides vivos receberam dose única de 5 UI de hCG/g (gonadotropina coriônica humana), por ocasião da aplicação da 2ª dose nas fêmeas. Os ovócitos das 14 fêmeas que responderam ao tratamento hormonal eram de cor acinzentada ou vinho, e aquelas que apresentaram alta taxa de fertilização mostraram distribuição de freqüência porcentual dos diâmetros com moda igual a 1900 µm. A taxa média de fertilização foi de 90%, e a de eclosão, 40%.

The objective of this study was to induce spawning in pirapitinga-do-sul, Brycon opalinus, with the application of hormones and to determine the pattern of oocyte diameter frequency distribution in females prepared to induction. One hundred and twenty spawners with 25.5 to 32.0 cm of length were placed in circular ponds of 10 m of diameter, at Estação de Aqüicultura de Paraibuna-SP of CESP. In order to determine the females apt to reproduction, samples of oocytes were obtained with plastic catheter and analysed. These oocytes were valued by colour, size, position of nucleus and oocyte diameter percentual frequency distribution. The males were selected by quality of semen. Twenty-nine females were selected and received two injections of SPE (salmon pituitary extract): the first, of 5 mg/kg and the other, of 10 mg/kg, with 12 hours of interval. The males that showed 90% of spermatic motility and 85% of life spermatozoa were selected and received 5 IU/g of hCG (human chorionic gonadotropin) when the females received the second dose. The oocytes of the 14 females that responded to the hormone treatment were gray or wine in colour, and in the females that presented high rates of fertilization, the oocyte diameter percentual frequency distribution showed mode of 1,900 mm. The average rate of fertilization was of 90% and that of hatching was 40%.

Estudos de reprodução induzida da piabanha, Brycon insignis, foram realizados em janeiro-fevereiro/96 e fevereiro/97, utilizando-se exemplares de 3 a 5 anos de idade, mantidos em cativeiro na Estação Experimental da Seção de Hidrobiologia e Aqüicultura, pertencente à CESP (Companhia Energética de São Paulo), localizada na cidade de Paraibuna, SP. As fêmeas selecionadas para indução da reprodução apresentaram ventre abaulado, papila genital saliente e avermelhada e 60% dos ovócitos com núcleo em posição excêntrica. Trinta e três fêmeas foram induzidas à reprodução com dose única de hCG de 5 UI/g (gonadotropina coriônica humana); 17 receberam duas aplicações de extrato bruto de hipófise de carpa, de 0,5 e 5,0 mg/kg, com intervalo de 10 horas entre as aplicações; 18 receberam 0,5 mg/kg de extrato bruto de hipófise de carpa e, após 10 horas, 5 UI/g de hCG; 5 fêmeas receberam dose única de solução salina a 0,9%. Cerca de 10 horas após a última aplicação hormonal, 43 fêmeas responderam positivamente aos tratamentos hormonais liberando óvulos por extrusão. A distribuição de freqüência porcentual dos diâmetros dos ovócitos da amostra inicial apresentou tendência unimodal, com moda em 1250 µm. Entre os hormônios testados, o mais eficiente foi o hCG, em dose única, e o menos eficiente, o de hipófise de carpa, com aplicação de duas doses. Os machos receberam dose única de 3 UI de hCG/g. Cada fêmea liberou, em média, 24.690 óvulos, que, após a fertilização e hidratação, se apresentaram esféricos, demersais e não adesivos, com diâmetro médio de 3785 a 3900 µm, grande espaço perivitelínico e córion resistente. A taxa de fertilização oscilou entre 20 e 96% e a de eclosão, entre 0 e 85%. A temperatura da água foi de 26ºC ± 1ºC.

Studies of induced spawning of piabanha, Brycon insignis, were developed from January to February/96 and February/97, with 3 to 5 years old individuals maintained in captivity. The selected females presented swollen abdomen and red genital papilla, 60% of oocytes with eccentric germinal vesicle. Thirty-three females were induced to spawning through a single dose of 5 IU/g of hCG (human Chorionic Gonadotropin); 17 females received two application: 0.5 and 5 mg/kg of crude carp pituitary extract in an interval of 10 hours; 18 received one application of 0.5 mg/kg of crude carp pituitary extract and, after 10 hours, 5 IU/g of hCG; and 5 females received a single dose of 0.9% saline solution. About 10 hours after the last hormonal application, 43 females responded positively to the hormonal treatment releasing eggs by extrusion. The percent frequency distribution of the oocytes diameter in the initial sample presented unimodal tendency, with mode in 1250 µm. Considering the different hormones utilized, the most efficient was hCG in a single dose and the less efficient was the hormone of carp pituitary applicated in two doses. The males received one dose of 3 IU/g of hCG. The females released a mean of 24,690 eggs, wich after fertilization and hydration presented an sphere form, were demesal and non-adhesive, with mean diameter from 3785 to 3900 µm, and had an expressive perivitelin space and a hard chorion. The rate of fertilization ranged from 20 to 96% and that of hatching, from 0 to 85%. The water temperature was 26ºC ± 1ºC.

This Study Concerns the morphological changes of the testes of "curimbatá", Prochilodus scrofa (Steindachner, 1881) at the beginning of sperm production, before and after the hormonal injections. We examined 25 three year old males that were reared in tanks at the Experimental Fish and Frog Culturing Station of Pindamonhangaba of the Fisheries Institute of São Paulo. The testes were sampled at the start of sperm production, after the first hormone injection (5 IU/g for weight of hCG), and 14 days before and after a second injection. Testicle fragments of these specimens were fixed and embedded in historesin. At the beginning of sperm production, the milky-white gonad showed consistem superficial vascularization, exceeding thick sperm under light pressure. Microscopically, the presence of spermatogonia, many spermatocytes, spemiatids and some tubules with spermatozoa were conspicuous. After the first hormonal dose, the gonads increased in volume, occupying most of the abdominal cavity superficial blood irrigation was evident, and sperm flowed easily out of the genital pore. Many spermatozoa were observed in the histology sections, along with spermatocytes and spemiatids, within the lumen of the seminal tubules. After 14 days, the testes exhibited decreased volume and pink-white coloration. Light microscopy revealed few spermatozoa and disarrangement of the structures forming the seminal tubules. After the second hCG dose, the testes again increased in volume, occupying most of the abdominal cavity. Some tubules were filled with spermatozoa whereas others showed reduced numbers of this cellular type.