Biofloc technology (BFT) provides an additional feed source for aquatic organisms through the conversion of waste in microbial flocs. Because of this, the suitable protein level in a diet for animals in this system could be different from those in conventional systems. Our objective was to determine the suitable protein level in the diet of Nile tilapia juveniles reared with BFT. Two experiments were carried out with tilapia weighing~10 g (first experiment) and about 50 g (second experiment) during 61 and 98 days respectively. Five crude protein (CP) levels (within 17% and 33%) were tested. The increment of CP resulted in a reduction in dissolved oxygen, pH, alkalinity and an increase in dissolved phosphorus, total suspended solids and total ammonium nitrogen. The crude protein level had a significant effect (p < 0.05) on animal performance. The linear response plateau model was the best fit for the final weight and weight gain data in the two growth phases. In conclusion, tilapia juveniles of 10-60 g and 60-230 g in biofloc can be fed on diets with 28% of CP (26% of digestible protein) and 22% CP (20% of digestible protein) respectively. K E Y W O R D Sbiofloc technology, growth performance, Nile tilapia, nutrition

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The effects of different water flow rates and feed training on the production of "pacamã" Lophiosilurus alexandri juveniles were evaluated. In the first experiment, nine day post-hatch larvae (n= 2,400) were stocked at a density of 5 larvae/L. Different water flow (F) rates were tested: F 1 = 180; F 2 = 600; F 3 = 1,300; and F 4 = 2,600mL/min. Artemia nauplii were offered as food during the first 15 days of active feeding. In the second experiment for feed training, 720 juveniles (total length of 22.2mm) were stocked at a density of 1.5 juveniles/L. A water flow rate similar to F 1 was used. The use of extruded dry diet was tested, and feed training was done with and without other enhanced flavors (Artemia nauplii or Scott emulsion). The water flow rates did not influence the survival or growth of L. alexandri. Cannibalism occurred during feed training. The worst survival, specific growth rate and high mortality were found with the use of extruded dry diet, while similar values were registered with the different feed training diets used. Reduced water flow rate can be used to lower water consumption during larviculture and feed training of L. alexandri.Keywords: feed training, juvenile production, larviculture, Lophiosilurus alexandri, water flow RESUMO Avaliaram-se os efeitos de diferentes fluxos de água e do condicionamento alimentar sobre a produção de juvenis de pacamã Lophiosilurus alexandri. Larvas com nove dias pós-eclosão (n=2.400) foram estocadas na densidade de 5 larvas/L. Diferentes fluxos (F) de água foram testados

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Caracterização genética de seis plantéis comerciais de tilápia (Oreochromis) utilizando marcadores microssatélitesPalavras-chave: tilápia, microssatélite, distância genética. ABSTRACTTwo hundred and thirty five individuals from six commercial stocks of tilapias (Ceará, Chitralada, Israel, Nilótica, Taiwan and Red) from the Southeastern region of the country were genetically characterized using five microsatellite loci. The results suggest large genetic difference among the stocks, estimated through the fixation allele index (Fst = 0.3263), and a considerable loss of heterozigosity occurs in most of the stocks, according to the population inbreeding coefficient (Fis=0.0486). The Israel and Nilótica stocks were genetically similar (Ig=0.6663), while Chitralada and Taiwan showed less genes in common (Ig=0.2463). The Red stock was the most distinct stock.

The biofloc technology (BFT) has recently gained attention as an economic and environmentally sustainable system for aquaculture. The use of BFT with salinized water could be used to minimize the negative effects of nitrogenous waste and improve the growth performance of Nile tilapia. This work evaluated the growth performance, survival, gill lesions, and fillet composition of tilapia fingerlings (Oreochromis niloticus) reared during 70 days with different salinities (0, 4, 8, 12, and 16 g/L) in a biofloc previously developed. The results indicated that the use of mature bioflocs alone was sufficient to avoid fingerling mortality due to nitrite peaks. Moreover, the salinized water, especially between 4 and 8 g/L (maximum points around 6 g/L), can be recommended in BFT to improve the growth performance of tilapia in the initial culture phase. The salinity level that was evaluated did not affect fillet composition nor the occurrence of gill lesions. The total ammonia nitrogen concentration was lower in freshwater than in salinized water (p < 0.05).Nitrite peaks in salinities of 12 and 16 g/L appeared later and were higher in comparison to other treatments. Considering minimal water exchange in BFT, the use of salinized water in this system may be environmentally viable. K E Y W O R D Sbiofloc technology, growth performance, Oreochromis niloticus, salinized water

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RESUMO -Neste trabalho, determinou-se o valor nutritivo de quatro alimentos energéticos (fubá de milho, sorgo, farelo de arroz integral e quirera de arroz) para juvenis de surubim. Os coeficientes de digestibilidade aparente da matéria seca (MS), proteína bruta (PB) e energia bruta (EB) foram avaliados pela metodologia de substituição do alimento numa ração-referência usando-se 0,1% de óxido crômico como indicador externo. Utilizaram-se 240 alevinos com 30 g de peso médio distribuídos em tanques apropriados para coleta de fezes. O delineamento foi inteiramente casualizado com quatro dietas, cada uma com quatro repetições. O coeficiente de digestibilidade aparente da matéria seca do fubá de milho foi de 62,3%; do farelo de arroz, 59,7%; da quirera de arroz, 40,4%; e do sorgo, 38%. Os coeficientes de digestibilidade da proteína bruta, nesta ordem, foram 87,4; 83,8; 85,3; e 81,1%; e os da energia bruta, 62,4; 66,4; 46,9 e 47,8%. Entre os alimentos avaliados, o que possui maior digestibilidade da matéria seca, proteína bruta e energia bruta é o farelo de arroz e o de menor digestibilidade, o sorgo.Palavras-chave: avaliação de alimentos, espécies carnívoras, pintado, Pseudoplatystoma Apparent digestibility coefficients of different energetic ingredients for surubim juvenilesABSTRACT -It was determined, in this work, the nutritional value of four energetic feeds (corn meal, sorghum, whole rice bran, and ground rice) for surubim juveniles. Apparent digestibility coefficients of dry matter (DM), crude protein (CP), and gross energy (GE) were evaluated by food replacement methodology in a reference-feeding using 0.1% of chromic oxide as an external marker. It was used 240 fingerlings with an average weight of 30 g distributed in tanks fitted for faeces collection.A complete random design with four diets, each one with four replicates, was used. Apparent digestibility coefficient of dry matter for corn meal was 62.3%; for rice bran, 59.7%; for ground rice, 40.4%, and for sorghum, 38%. Digestibility coefficients for crude protein were, in this order, the following: 87.4, 83.8, 85.3 and 81.1% and digestibility coefficient for gross energy were: 62.4, 66.4, 46.9 and 47.8%. Among the evaluated feeds, the one with the highest digestibility of dry matter, crude protein, and gross energy is the rice bran and the one with the lowest digestibility is the sorghum.Key Words: Brazilian catfish, carnivorous species, feed evaluation, Pseudoplatystoma IntroduçãoNo Brasil, apesar da crescente demanda por rações comerciais para o surubim (Pseudoplatystoma sp), existem poucos trabalhos que tratam da avaliação de alimentos para essa espécie. A falta de dados concretos sobre a avaliação de alimentos e exigências nutricionais faz com que as deficiências na alimentação e nutrição desses peixes sejam responsáveis por altos índices de mortalidade, baixa eficiência alimentar e baixo desempenho (Teixeira, 2008).A ração é muito importante, pois, quando formulada adequadamente, permite maior eficiência no uso de seus nutrientes tornando a composição...