ABSTRACT Effects of four feeding regimes on the development and feed intake, survival, productivity, and growth of Macrobrachium amazonicum larvae were investigated. Larvae were fed from stage II to IX, as follows: Artemia nauplii + inert diet during the entire larval cycle (AIn); Artemia nauplii for the entire larval cycle + inert diet from stage V onward (A/AIn); Artemia nauplii until stage IV + inert diet from stage IV onward (A/In); and only inert diet for the entire larval cycle (In). Each feeding regime (treatment) was carried out in three 50-L rectangular black tanks, set up in a recirculating system, filled with 10 salinity brackish water, and stocked at 81.8±0.8 larvae/L. The larval stage index, occurrence of Artemia nauplii and/or inert feed into the digestive tract, survival (number of larvae and postlarvae), productivity (number of postlarvae/L), and weight gain (mg) were evaluated. Larval development was similar in treatments AIn, A/Ain, and A/In, but was delayed in treatment In. Artemia nauplii were ingested by larvae irrespective of developmental stages, while inert feed was ingested only from stage III onward. Survival and productivity were higher in treatment AIn and decreased according to the number of days larvae were fed Artemia nauplii. Macrobrachium amazonicum larvae are omnivorous and polytrophic, but live feed is essential in the first stages and act as a complementary diet in the last half of larval cycle. There is a potential for inert diet to replace Artemia in the last phase of development if the nutrient composition matches larvae requirements. The combination of Artemia nauplii and inert diet during all larval cycles is the best management to maximize productivity.

O objetivo deste trabalho foi avaliar a composição química e os teores de ácidos graxos do camarão-amazônico e do camarão-da-malásia. Após cultivo de quatro meses, com a mesma dieta para ambas as espécies, os principais ácidos graxos saturados foram o palmítico e o esteárico. O oleico foi o principal ácido graxo monoinsaturado, e o eicosapentaenoico e o docosahexaenoico foram os ácidos poli-insaturados mais abundantes. O camarão-amazônico apresenta níveis mais elevados de proteínas e de ácidos graxos poli-insaturados do que os do camarão-da-malásia, o que mostra seu potencial para a aquicultura.

The objective of this work was to evaluate the chemical composition and fatty acid contents of Amazonian and giant river prawns. After four-month farming, with the same diet for both species, palmitic and stearic acids were the main saturated fatty acids. Oleic acid was the main monounsatured fatty acid, and the eicosapentaenoic and docosahexaenoic acids were the most abundant polyunsaturated acids. Amazonian prawn has higher levels of protein and polyunsaturated fatty acids than those of the giant river prawn, which shows its potential for aquaculture.

In this article the length growth curves of Macrobrachium rosenbergii (De Man, 1879) held in different population densities were analysed. Postlarvae prawns were stocked into five 0,02 ha earthen ponds at densities of 4, 8, 12, 16 and 20 ind./m² during six months. Forthnightly, the mean total length of animals from each pond were obtained by means of random samples. For each population the length growth curves and the instantaneous growth rate expressions were determined. The growth rate and the asymptotic maximum length decreased with the stocking density raised. This effect is greater when the density ranges in low levels. The growth decrease can be due to intraspecific competition for life resources and to negative interactions between individuals, as aggressive or social behavior, that increase with the increase prawns density.

In this paper, the relative growth of Macrobrachium acanthurus (Wiegmann, 1836) (Crustacea, Decapoda, Palaemonidae), is presented; the cephalothorax length/abdominal length, telson length/abdominal length and abdominal length/total length relashionships were determined. The adjusted equations showed a isometric growth pattern. There are no changes in these relationships during the animals growth that may be significant in the maximization of the meat's profit.

In this paper, the fecundity in Macrobrachium acanthurus (Wiegmann, 1836) of the Ribeira de Iguape river (Southern Brazil) (Crustacea, Decapoda, Palaemonidae), is presented. The mean individual fecundity of the population was estimated. Fecundity was related to either length and/or weight. Our data showed that this species presents high fecundity and is thus suitable for comercial culture. The fecundity/length and fecundity/weight relationships obtained are: F = - 14 712 + 2 311,8 L and F = -1493,9 + 798,76 W