-This study aimed to evaluate economically the inclusion of prebiotics, probiotics and symbiotics in diets of Nile tilapia (4.07 ± 0.30 g), at two stocking densities (0.6 and 1.2 kg m -3 ). A total of 288 fish were distributed over 32 tanks (40 L) in a completely randomised design, in a 2 x 4 factorial (stocking density x additives), with four replications, over six weeks. The following were evaluated: total feed consumption (FC), final biomass (FB), relative gain in biomass (RGB), apparent feed conversion (AFC), survival rate (SUR), average cost of feed per kg of live weight gain (ACF), total cost of feed (TCF), total cost of production (TCP), gross income (GI), operating profit (OP) and economic efficiency index (EEI). No effect was seen on the evaluated parameters from the interaction (p>0.05) between stocking density and inclusion of the feed additives. No influence was observed (p>0.05) on SUR from the stocking density, although this significantly influenced the parameters FB, FC, RGB, AFC, ACF, TCF, TCP, GI and OP. There was no significant influence from the inclusion of prebiotics, probiotics and symbiotics on FC, SUR and TCF, however there was an influence (p<0.05) on the parameters FB, RGB, AFC, ACF, TCP, GI and OP. The control diet at the higher density displayed the worst EEI. The best EEI was obtained by fish at the lower density which received feed with added probiotics and symbiotics. The best indices of economic and zootechnical performance obtained demonstrate the economic viability of including prebiotics, probiotics and symbiotics in the diets of Nile tilapia.

The tambaqui (Colossoma macropomum) is a fish of primary importance in South American aquaculture, principally in the Amazon region and has a particularly unique diet in the wild. Oryza spp, or Wild rice as it is commonly known, is native to the floodplains of muddy rivers in the Amazon region. The aim of this study was to analyze the physical performance and the effects of dietary levels of Oryza spp. via the hematological parameters, total food intake, conversion efficiency, growth ratio and swimming performance of this fish. Diets containing 45% Oryza spp. induced the best performance in tambaqui. Diets containing 15% and 30% did not affect these indices, thus indicating that this amount of Oryza can be used as an alternative energy source for this important species within Brazilian aquaculture.

Dwarf rainbowfish (Melanotaenia praecox) are an ornamental fish with a high added value and considerable commercial interest. However, little information is known about the organism's reproductive biology, especially the early stages of embryonic development (initial ontogeny). Melanotaenia praecox embryos were examined throughout development to describe the dwarf rainbowfish initial ontogeny. Eggs were incubated at 28°C, and observations were recorded at pre-determined times. Development stages were identified and classified according to morphophysiological characteristics. The initial size of the eggs ranged between 0.99 and 1.04 mm. Oil droplets were observed in the eggs, and fixing filaments for adhesion were observed in the corium. Embryonic development was similar to that of other species in the genus Melanotaenia, in which hatching begins 119.50 h post-fertilisation or 3405.75 degree-h post-fertilisation. The main features of the newly hatched larvae were excellent swimming activity, a reduced yolk sac, mouth movement and an apparently functional digestive system.

Rev. Bras. Saúde Prod. Anim., Salvador, v.13, n.3, p.880-893 jul./set., 2012 http://www.rbspa.ufba.br ISSN 1519 9940 880 Ontogeny and embryonic description of Betta splendens, Perciformes (Regan, 1910)Ontogenia e descrição embrionária em "Betta splendens"

RESUMOConduziu-se um experimento com o objetivo de avaliar a influência do período de coalimentação na sobrevivência e no crescimento de larvas de Betta splendens. As larvas foram alimentadas com náuplios de Artemia durante sete dias e, posteriormente, submetidas aos seguintes tratamentos: jejum contínuo; ração contínua; quatro dias de coalimentação + 14 dias de ração; oito dias de coalimentação + 10 dias de ração; 12 dias de coalimentação + seis dias de ração; náuplios de Artemia durante todo o período experimental. Os valores das variáveis de desempenho das larvas do tratamento 12 dias de coalimentação + seis dias de ração e do tratamento náuplios de Artemia foram superiores aos demais tratamentos, exceto para sobrevivência, em que não houve diferença significativa com o tratamento oito dias de coalimentação + 10 dias de ração. Considerando-se apenas o tempo de oferta de Artemia (em dias), obteve-se a equação de regressão para as variáveis analisadas. A sobrevivência e a taxa de crescimento específico (TCE) apresentaram efeito quadrático, e as demais variáveis apresentaram efeito linear. O ponto de máxima para sobrevivência foi de 21,7 dias (88,92%) e para TCE foi de 26,2 dias (23,47% dia -1 ). O período de co-feeding influencia no crescimento e na sobrevivência de larvas de Betta splendens. Após o período de 19 dias de oferta de alimento vivo, com 12 dias de coalimentação, as larvas estão aptas a aproveitar de maneira eficiente o alimento inerte sem prejuízos ao crescimento e à sobrevivência.Palavras-chave: peixes ornamentais, Betta splendens, larvicultura de peixes, coalimentação, transição alimentar ABSTRACT An experiment was carried out to evaluate the influence of the period of co-feeding on survival and growth of Betta splendens larvae. The following strategies for co-feeding were used: continuous fasting, 18 days of inert diet, 4 days of co-feeding + 14 days of inert diet; 8 days of co-feeding + 10 days of inert diet; 12 days of co-feeding + 6 days of inert diet, nauplii of Artemia throughout the experiment period. The values of performance variables for larvae with 12 days of treatment for co-feeding + 6 days of inert diet and the nauplii treatment with