The effects of the intensification on the performance of the Amazon River prawn hatchery carried out in a simple recirculation system were investigated. Newly hatched larvae were stocked in 120 L tanks at 80, 100, 120 and 140 larvae L⁻¹ in a closed recirculating system. The experiment used a randomized block design with five replicates. An exponential equation was adjusted to express the relationship between the stocking density and productivity (postlarvae L⁻¹). The development, larval quality, survival and postlarval (PL) dry weight did not significantly differ among the treatments (p > 0.05). When 80 larvae were stocked, the productivity (54 ± 11 PL L⁻¹) was lower than those at higher densities (p < 0.05). Stocking 120 and 140 larvae L⁻¹ resulted in higher productivities (75 ± 18 and 80 ± 17 PL L⁻¹, respectively) with a lower use of Artemia nauplii to produce each postlarvae (~1200 Artemia nauplii PL⁻¹). The maximum mean M. amazonicum postlarval production estimated by the exponential model was 93 PL L⁻¹. This means that despite the increase in stocking density, productivity tends to stabilize. The results showed that M. amazonicum tolerates high intensification in recirculating hatchery systems based on a crushed shell bed biofilter, and the intensification optimizes Artemia use.

We present herein the results of a brief field survey of species of Macrobrachium Spence Bate, 1868 in three points of the northern portion of the lower Parnaíba River basin. The northern region of the lower Parnaíba River basin is part of the Environmental Protection Area Delta do Parnaíba and comprises several lakes, coastal lagoons, and the delta of the Parnaíba River. In total, we found five species: Macrobrachium acanthurus (Wiegmann, 1836), Macrobrachium amazonicum (Heller, 1862), Macrobrachium carcinus (Linnaeus, 1758), Macrobrachium jelskii (Miers, 1877), and Macrobrachium olfersii (Wiegmann, 1836) all of which are new records for the region.

O experimento foi conduzido na Universidade Estadual Paulista, Laboratório de Peixes Ornamentais do Centro de Aqüicultura da Unesp, Jaboticabal, Estado de São Paulo, com o objetivo de avaliar o desempenho produtivo do acará bandeira (Pterophyllum scalare), alimentados com dietas processadas de três formas (farelada, peletizada e extrusada). Foram utilizados 240 peixes distribuídos em 24 aquários de 40 L, alimentados com uma dieta contendo 28% de PB e 4000 kcal kg^-1 de EB. Avaliou-se o peso final médio, ganho de peso, taxa de crescimento específico, consumo de ração e conversão alimentar. Ao final de oito semanas, não houve diferença significativa no desenvolvimento dos peixes alimentados com dietas extrusada e peletizada. Os alimentados, entretanto, com dieta farelada apresentaram baixa taxa de crescimento específico. A taxa de conversão alimentar foi melhor em indivíduos alimentados com dieta extrusada. Nas condições presentes neste estudo dietas extrusadas e peletizadas são adequadas para o crescimento e manutenção do acará.

Aquaculture intensification increases waste generation, whose composition may influence methane emissions. This study evaluated the effects of dietary protein and energy sources on nutrient digestibility and the methane production potential of Nile tilapia feces. Nine experimental diets were tested in digestibility assays: one reference diet (RD) and eight test diets containing 80% RD and 20% of an animal or plant ingredient. Feces were collected and subjected to batch anaerobic digestion. Soybean meal and meat and bone meal diets showed the highest apparent digestibility coefficients (ADC) for dry matter (84.1 and 82.6%) and energy (87.3 and 87.9%), whereas poultry by-product meal presented the lowest values. Crude protein digestibility ranged from 78.74% for blood meal diet to 94.3% for soybean meal diet. Feces from poultry by-product meal generated the highest methane potential (260.9 L kg⁻¹ VS), whereas blood meal exhibited the highest methane production per unit of COD removed (310.5 mL g⁻¹ reduced COD). After 10 days, poultry by-product meal accumulated the highest biogas volume, while soybean meal and blood meal showed the lowest. Principal component analysis suggested inverse relationships between nutrient digestibility and fecal biodegradability. Overall, dietary composition influenced nutrient digestibility, physicochemical characteristics of fish feces, and their methane generation potential. This integrated assessment suggests that feed formulation could contribute to strategies aimed at reducing the methane generation potential of aquaculture wastes.