more niacin, twice as much riboflavin, and fifty percent more phosphorus. Camu-camu has an exceptional value that has justified planting in Peru and Brazil for export of "natural vitamin C." This provides good opportunities for local economies, including the utilization in fish diets, as the source of vitamins and phytochemicals.
The palm of aguaje is a massive tree that can grow to over 100 feet tall in the Amazon rainforest. The fruit of aguaje is a sub-globose "pineapple" of 5 to 7 cm in length, 4 to 5 cm in diameter, brown to dark-red in color, 40 to 85 g in weight, 10 to 21% yellow to red-orange pulp, and 1 to 2 seeds per fruit. The fruits are eaten raw or processed, making a sweet paste used for beverages and ice creams. Fruits and seeds also yield edible oil. The fiber of the palm is used to build the roof of houses. The leaf is used in handicrafts. The trunk is used to obtain meal with starch of good quality and is also used in paper processing. This native plant is not only important for humans, but it is an essential fruit in the diets of the wild animals from the rainforest.
Dispersal fruits and seeds of tropical plant species, such as aguaje and camu-camu, have also been reported as part of the diet of frugivorous fish of the Amazon; in particular, the native Amazon fishes paco, Piaractus brachypomus, and gamitana, Colossoma macropomum. Aquaculture of these fish species has to be developed at extensive and semi-intensive levels because of their high growth potential mainly in earthen ponds or floating cages (Saint-Paul, 1992). The information about the nutritional requirements of Neotropical freshwater species with economical importance, such as serrasalmids, is still scarce.
These Characidae have a commercial value because of their high growth rate and the quality of their flesh (Saint-Paul, 1992; Vieira and Johnston, 1996). During the Ninth Work Plan, we successfully induced ovulation and spermiation of P. brachypomus using luteinizing hormone-releasing hormone analog (LHRHa). Both genders were injected with two doses of LHRHa. Concentration of the preparation was 0.0042 mg of equivalents of active hormone per milliliter. Males and females were injected with 1 ml kg-1 and 2.6 ml kg-1, respectively. The priming dose (50 and 10% in males and females, respectively) was administrated in the morning, whereas the resolving dose (50 and 90% in males and females, respectively) was injected at 2200 h. Oviposition was observed within 8 to 16 h following the resolving dose of the hormone, and survival at 13 h of incubation amounted to 68.5 ± 25%. Our challenge now is to rear larvae of paco and gamitana using formulated dry feeds. This is important because survival of larval paco stocked directly to ponds was very low in IIAP's experience. Information on the first feeding of Characidae is scarce. Recently, a feeding experiment was carried out to determine the relationship between
live Artemia feeding levels and growth rate in pre-weaning C. macropomum larvae (Sevilla and Gunther, 2000). However, Canzi et al. (1992) and Yamanaka (1988, in Canzi et al., 1992) reported that artificial diets are readily accepted by P. mesopotamicus. Therefore, we proposed to investigate the potential for first feeding of C. macropomum and P. brachypomus using commercial and experimental diets. Preliminary experiments in 2000 that we carried out in IIAP-Iquitos confirmed the acceptance of formulated diets and growth of paco larvae.
The second objective of this study is focused on the controlled reproduction of two catfish species, Pseudoplatystoma fasciatum and P. tigrinum, which are of interest as new aquaculture species in South America (Kossowski, 1996). In Peru, spawning of both species occurs in February and March (Alc‡ntara-Bocanegra, pers. comm., 2001). In P. fasciatum, the oocyte size was used to evaluate the maturity of the gonads, and a diameter of 1.8 mm indicated the readiness of the gonads (Kossowski, 1996). Final maturation and ovulation was achieved in several catfish species from South America using carp pituitary extracts or pituitary hormones (Cardoso et al., 1995; Kossowski, 1996). However, to the best of our knowledge, no information is available on the profiles of plasma sex steroids in both target species, and we could possibly use this information to synchronize ovulation and spermiation in these fish (Dabrowski et al., 1996). The annual changes in the blood plasma steroids as well as the surge preceding spermiation and ovulation (maturational hormones) can contribute to a better un
