RESUMO - O objetivo deste trabalho foi avaliar a aplicabilidade da técnica de eletroejaculação para manejos de inseminação artificial, bem como o potencial ejaculatório de cada um dos tipos morfológicos de machos adultos do Macrobrachium rosenbergii. Estímulos elétricos foram aplicados em 48 exemplares de camarão-de-água-doce, recém capturados em viveiros de engorda, para melhor compreensão do comportamento reprodutivo de cada um: os de quela azul (BC), sexualmente ativos e dominantes; os de quela laranja (OC), sexualmente inativos; e os pequenos (SM), com comportamento oportunista, os quais somente realizam a cópula, caso a corte da fêmea tenha sido previamente realizada por um macho BC. Não houve diferença entre as freqüências de ejaculação observadas para machos OC e BC, que foram 85 e 100%, respectivamente, demonstrando que os primeiros possuem potencial fisiológico para a cópula. A freqüência de 46,2%, nos testes de eletroejaculação bem sucedidos para os indivíduos SM, foi mais baixa em relação aos outros dois morfotipos. A freqüência de 79,2% de ejaculações, obtida entre o total de animais usados, demonstrou o potencial dessa técnica para a obtenção de espermatóforos em quantidade suficiente para a manutenção de fêmeas ovadas em épocas de baixas temperaturas.

ABSTRACT - The objective of this work was to evaluate the electroejaculation applicability for artificial insemination as well as the ejaculatory potential of each Macrobrachium rosenbergii adult male morphotype. Electrical stimuli were applied to 48 newly pond - reared individuals of freshwater prawn for a better comprehension of each one's reproductive behavior: the blue claw males (bc), sexually active and dominant; the orange claw (OC), sexually inactive, and the small ones (SM), with opportunist behavior, succeeding to copulate only if a bc male has made the courtship first. There was no difference among the ejaculation frequencies for OC and BC males, which were 85 and 100%, respectively, demonstrating that the former morphotype has physiological potential for mating. The frequency of 46.2% of successful eletroejaculation tests observed for SM individuals was lower in relation to the two other morphotypes. The frequency of 79.2% of ejaculations observed for all used animals demonstrated the technique potential for the attainment of a sufficient amount of spermatophores prior to the maintenance of gravid females during cold temperature seasons.

Parauchenipterus striatulus is a representative of the freshwater catfish with wide distribution in the South America region. Despite of being a very abundant fish in rivers and reservoirs of this region, little is known about its biology and ecology. In Ribeirão das Lajes reservoir (22º42'S - 22º50'S, 43º53'- 44º05' W, Rio de Janeiro), the Rio de Janeiro state's largest hydroelectric reservoir, this species is very abundant, representing about 40% of the total experimental fish catches using gill nets. This paper aims to assess aspects of the reproductive cycle of this species describing the gonadal stages, gonadosomatic index, weight-length relationship and condition factor. Fish sampling were carried out bi-monthly, between April 1996 and May 1997. Gill nets used were 100 m long, 4 m high with mesh size between 25 and 65 mm. Macroscopic analysis of 339 individuais were performed for the determination of 5 maturation stages, for both sexes (immature, maturation I, maturation II, ripe, spawned (females) and emptied (males). The gonadosomatic index for both sexes was higher from October to March, suggesting a long spawning period while the condition factor was higher from February to June, showing an inverse relationship between these two parameters. Weight-length relationship for males was W=0,0095L3,C862and for females W= 0,0116L3,126, and no significam differences were shown between sex with reference to the alometry coefficient.