ABSTRACT This study aimed to describe a procedure for sampling, reproduction, and first feeding of the Neotropical catfish Pseudopimelodus mangurus, an endangered fish species. Wild adult P. mangurus specimens were collected in the Mogi Guassu River and subsequently induced to spawn in laboratory conditions. After hand-stripping, the females, the average weight of the oocytes was 143 ± 1.6 g, with a fecundity of 718 ± 49.8 oocytes g-1. The diameter of the oocytes non-hydrated was 1226.3 ± 47.7 μm to 1761.2 ± 26.4 μm after hydration. The fertilization rates were 98.00 ± 0.63%, and the hatching rate was 68.94 ± 11.83%. The first feeding was made three days post-hatching with six different treatments, in which the best results arose with sequential feeding with Artemia nauplii, Astyanax altiparanae and Prochilodus lineatus larvae. This condition resulted in a final length of 2,012.7 ± 44.8 μm by the 10th day of the experiment, higher survival (65 ± 0.9%) and lower cannibalism rate (14 ± 0.3%). The data obtained in this study is important for the establishment of reproductive biotechniques, mass production of P. mangurus, and future establishment of ex-situ GenBank.

ABSTRACT The objective with this study was to evaluate the liver histology and hematological parameters of female Rhamdia quelen fed diets supplemented with different oils: 5% marine fish oil, 5% refined palm oil, 5% soybean oil, and a combination of the three. The lipid vacuolization (steatosis) in the liver was analyzed according to a score of vacuolization when: 0 = absence, 1 = reduced, 2 = intermediate, and 3 = intense. At the end of the experiment, females (n = 10) were selected from each treatment (two per cage), and the blood was collected for erythrocyte and biochemical analysis. Lower vacuolization indices in the liver were observed at the beginning of the experiment. However, with time, the presence of vacuoles was more evident but presented similar morphology among all treatments. The blood parameters were also not influenced by the different diets, except for glucose levels, which was higher in the treatment with the mixture of oils. The absence of differences regarding liver morphology (steatosis) and hematological parameters indicates that the replacement of fish oil by vegetable oils could be performed without damage to the health of R. quelen females.

ABSTRACT The effects of a diet supplemented with 5% marine fish oil, 5% refined palm oil, 5% soybean oil, and a combination of the three on reproductive parameters of females Rhamdia quelen was investigated. Spawning was artificially induced to evaluate rates of fertilization, hatching and larvae normality. Fatty acid profiles of the diets, ovaries and oocytes were determined. A higher spawning rate (%) was observed for diets containing fish oil (78.65 ± 3.60) and palm oil (77.15 ± 3.97), followed by oil mix (65.46 ± 4.57). The diet containing soybean oil was associated with significantly lower fertilization (60.14 ± 5.66; P < 0.05) than the palm and fish oil diets. Lower fertilization may be explained by a high level of n-6 fatty acids in the diet, which possibly accelerate the oocyte maturation. Satisfactory fecundity (P > 0.05) were observed for all tested diets, whit 289.77 ± 23.90 (palm oil) until 323.31 ± 38.45 oocytes g-1 body weight (fish oil). The treatments were not shown to influence oocyte size, larval size or rate of larva deformity. Oocyte fatty acid composition was like that of gonads. Docosahexaenoic (DHA; C22:6 n-3) fatty acid was preferentially deposited in ovaries and oocytes. Ratios of n3/n6, DHA/EPA, EPA/ARA, did not affect the reproductive performance of females. Therefore, regarding female reproductive performance, the vegetable lipid sources tested are suitable for being used in R. quelen diet, and palm oil, in particular, is considered an excellent alternative to fish oil.

In this study we examined the effects of the maternal age on the fecundity (absolute and relative), egg production, and fertilization rates of Nile tilapia (Oreochromis niloticus). Females were divided into three groups: Group 1 (6 years old), Group 2 (3 years old), and Group 3 (8 months old). Males of eight months were used in all groups. Twice a week, the females' mouths were examined, and if they had eggs, these were removed and transferred to 2-L incubators. No difference was observed in the absolute fecundity between the different maternal age groups. Relative fecundity and egg production was greater in Group 3 (8 months) and fertilization rates were lower in Group 1 (6 years). Younger tilapias are more viable for egg production, because they have better reproductive indexes.