Jaús Zungaro jahu (Ihering, 1898), mantidos em estação de piscicultura, foram induzidos à reprodução com extrato bruto de hipófise de carpa. Seus ovos são telolécitos, arredondados (1,6 ± 0,1 mm de diâmetro), demersais, livres e cobertos por uma capa gelatinosa com 0,4 mm de espessura. O índice gonadossomático (peso da ova : peso total do peixe) de 2,8 foi semelhante ao de outros Pimelodidae. O número de ovos x g de ova-1 foi 804 ± 144. A eclosão dos embriões ocorreu 14,5 h pós-fertilização à temperatura de 27,3 ± 0,4º C. Os embriões recém-eclodidos apresentaram 3,9-4,3 mm de comprimento total (CT). Dezoito horas pós-eclosão (HPE) e 5,3 ± 0,1 mm CT, a retina estava pigmentada, a boca aberta e a flexão da notocorda tinha se iniciado. Às 36 HPE (6,4 ± 0,2 mm CT), observaram-se cromatóforos fusiformes alinhados verticalmente na nadadeira primordial; a notocorda já se encontrava flexionada. O saco vitelínico encontrava-se quase que inteiramente absorvido às 48 HPE (7,3 ± 0,2 mm CT). Com 128 HPE (8,6 ± 0,6 mm TL), as nadadeiras peitoral, dorsal, adiposa, caudal, anal e pélvica estavam formadas e a nadadeira primordial já havia sido reabsorvida. Com 224 HPE (16,6 ± 2,5 mm CT), a metamorfose se completou e as larvas se transformaram em juvenis.

Hatchery-kept catfish jahus Zungaro jahu (Ihering, 1898) were induced to spawn with carp pituitary extract. The telolecithal eggs were round (1.6 ± 0.1 mm in diameter), demersal, free, and covered with a 0.4 mm-thick jelly coat. The gonadosomatic index of 2.8 was comparable to that of other Pimelodidae. The number of eggs x g of ova-1 was 804 ± 144. Hatching occurred 14.5 h after fertilization, at a temperature of 27.3 ± 0.4º C. The newly-hatched embryos measured 3.9-4.3 mm of total length (TL). At 18 h post-hatching (HPH; 5.3 ± 0.1 mm TL), the retina was pigmented, the mouth opened and dorsoflexion of the notochord had initiated. At 36 HPH (6.4 ± 0.2 mm TL), fusiform chromatophores were vertically arranged in the primordial fin fold and the notochord was dorsoflexed. The yolk sac was almost exhausted by 48 HPH (7.3 ± 0.2 mm TL). At 128 HPH (8.6 ± 0.6 mm TL) the pectoral, dorsal, adipose, caudal, anal, and pelvic fins were readily observable whereas the primordial fin fold was no longer visible. At 224 HPH (16.6 ± 2.5 mm TL), the metamorphosis was completed and the larvae had acquired the juvenile appearance.

In South America, one important symptom of the failure of fish passages to sustain fish migratory recruitment is the inability of eggs and larvae to reach the nurseries. This is especially so when the breeding areas are located upstream of a reservoir, and the floodplain is downstream of the dam. Therefore, the transport of fish larvae and eggs across reservoir barriers is a key factor in the development of effective conservation strategies. In this paper, we evaluate the potential for migratory fish larvae and egg transportation across a small size reservoir in eastern Brazil. We sampled fish daily between 15th October 2002 and 15th February 2003 (spawning period) in the Mucuri River, immediately upstream of the reservoir and downstream of the Santa Clara Power Plant dam. Our study was the first to indicate the possibility of successful larval passage through the reservoir of a hydroelectric reservoir and dam in South America, and showed that the passage of migratory fish larvae was associated significantly with residence time of water in the reservoir. The relatively short water residence time and elevated turbidity of the Santa Clara's reservoir waters during the rainy season certainly contributed to the successful passage, and can be considered as key factors for a priori evaluations of the feasibility of a downstream larval passage.