Influence of feeding period on consumption and weight gain of pirarucu

O objetivo deste trabalho foi verificar o período preferencial de consumo alimentar do pirarucu, Arapaima gigas, e a influência de diferentes turnos de alimentação no consumo e ganho de peso dessa espécie. Foram testados três tratamentos: alimentação diurna (peixes alimentados às 9h e 15h), alimentação noturna (peixes alimentados às 21h e 3h) e alimentação contínua (peixes alimentados às 9h, 15h, 21h e 3h). Cada tratamento foi avaliado em triplicata, com cada unidade experimental formada por oito peixes, com peso médio de 313 g, estocados em tanques-redes de 1 m3 (1x1x1 m). Os nove tanques-redes foram alocados em um viveiro escavado de 120 m2. O experimento durou 60 dias. A alimentação contínua promoveu maiores ganhos de peso e biomassa, taxa de crescimento específico e consumo total. Os tratamentos alimentação diurna e alimentação noturna apresentaram ganho de peso semelhante, porém, a alimentação diurna apresentou a melhor conversão alimentar. O período preferencial de alimentação do pirarucu foi o noturno, principalmente no começo da noite. Os dados deste estudo indicam que o horário de preferência alimentar não é o melhor horário de alimentação do pirarucu, em uma criação comercial. O período de alimentação mais indicado para a espécie, baseado na capacidade de conversão alimentar, é o diurno.The objective of this study was to verify pirarucu Arapaima gigas preferential time of feeding, and the influence of different feeding periods on consumption and weight gain of this species. Three treatments were tested: diurnal feeding (fish fed at 9h and 15h), nocturnal feeding (fish fed at 21h and 3h), and continuous feeding (fish fed at 9h, 15h, 21h and 3h). Each treatment was evaluated in triplicate, and each trial unit had eight fishes with 313 g average weight, stoked into a 1 m3 (1x1x1 m) net cage. The nine net cages were located on a 120 m2 earth pond. The trial lasted for 60 days. Continuous feeding promoted the highest weight and biomass gain, specific growth rate and feed consumption. Nocturnal and diurnal feeding treatments showed similar weight gain; however, diurnal feeding had the best feed conversion ratio. The preferred feeding time for pirarucu was the nocturnal period, mainly at the beginning of night. Data from this study indicated that the preferred feeding time is not the best one for feeding pirarucu on a commercial husbandry. The most indicated feeding period for this species, based on its feed conversion capacity, is diurnal period

Stocking density effect on growth homogeneity of juvenile pirarucu in confined environments

O objetivo deste trabalho foi avaliar o efeito da densidade de estocagem sobre a homogeneidade do crescimento de juvenis de pirarucu (Arapaima gigas) em tanques-rede de pequeno volume. Foram usados 12 tanques-rede de 1 m3 em um viveiro de 120 m2 perfazendo três tratamentos (15, 20 e 25 peixes/m3) com quatro repetições. Os peixes foram estocados com peso médio inicial de 10,1±0,3 g e distribuídos homogeneamente (p > 0,05) entre os tratamentos. Os coeficientes de variação do crescimento e do fator de condição não apresentaram diferenças significativas (p > 0,05) ao contrário do consumo e da conversão alimentar aparente (p 0.05) between treatments. Coefficient of variation for growth and condition factor did not present significant (p > 0.05) differences, contrary to consumption and apparent feed conversion (p < 0.05). Consumption was inversely proportional to the increment of density, indicating that stockings densities increases are favorable to a better feed use. There were not any observed behavior differences between treatments. Juveniles pirarucu growth was not influenced by the stocking density or intra-specifics interactions

Tolerância de juvenis de pirarucu ao aumento da concentraç ão de amônia em ambiente confinado

The objective of this work was to evaluate the tolerance of pirarucu (Arapaima gigas) juveniles to increasing concentrations of ammonia in the water. Eight fish (2.6±0.4 kg and 70.5±4.1 cm length) were evenly distributed in four tanks (0.8x0.9x2.6 m) with 410 L of water buffered with Na2PO4 (0.1 M) and HCl (0.1 M), where they were kept for 33 days. Ammonia concentrations in the fish blood plasma and in the water were determined by the salicilate method. Plasma glucose and ammonia levels increased proportionally to the concentration of ammonia in the water. Pirarucu juveniles tolerate high concentrations of ammonia in the water

Tolerance of pirarucu juveniles to increasing ammonia concentration in a closed environment

O objetivo deste trabalho foi avaliar a tolerância de juvenis de pirarucu, Arapaima gigas, a concentrações crescentes de amônia na água. Oito peixes (2,6±0,4 kg e 70,5±4,1 cm de comprimento) foram distribuídos aleatoriamente em quatro tanques (0,8x0,9x2,6 m) com 410 L de água tamponada com Na2PO4 e HCl, ambos a 0,1 M, onde ficaram por 33 dias. As concentrações de amônia no plasma sanguíneo dos peixes e na água foram determinadas pelo método do salicilato. A glicose plasmática e os níveis de amônia aumentaram proporcionalmente à concentração de amônia na água. Juvenis de pirarucu toleram altas concentrações de amônia na água.The objective of this work was to evaluate the tolerance of pirarucu (Arapaima gigas) juveniles to increasing concentrations of ammonia in the water. Eight fish (2.6±0.4 kg and 70.5±4.1 cm length) were evenly distributed in four tanks (0.8x0.9x2.6 m) with 410 L of water buffered with Na2PO4(0.1 M) and HCl (0.1 M), where they were kept for 33 days. Ammonia concentrations in the fish blood plasma and in the water were determined by the salicilate method. Plasma glucose and ammonia levels increased proportionally to the concentration of ammonia in the water. Pirarucu juveniles tolerate high concentrations of ammonia in the water

Níveis de proteína bruta para juvenis de pirarucu

The objective of this work was to verify the effect of four protein levels on pirarucu, Arapaima gigas, growth performance. One hundred and twenty pirarucu juveniles, with an average weight of 120.6±3.5 g, were stocked into 12 floating cages with 1 m3 (ten fish per cage), in a complete randomized design with four treatments (32.7%, 39.3%, 43.4% and 48.6% crude protein), in three replicates each. After 45 days, results showed that diet with highest protein level (48.6%) produced a better weight gain, specific growth rate, and differentiated body composition. Feed conversion and protein efficiency ratios did not show any differences among treatments. The dietary protein level required to produce maximum growth is 48.6%

Biomassa sustentável de juvenis de pirarucu em tanques-rede de pequeno volume

The objective of this work was to estimate the sustainable biomass of pirarucu Arapaima gigas (Cuvier, 1829) juveniles kept in small volume net cages. During 200 days four 1-m3 net cages were stocked with 21 fish/cage and had an initial total biomass of 0.84±0.14 kg (21 fish/cage). The net cages were placed in a 50-m2 pond with constant water flow. Conditioning factor, feed conversion, specific growth rate and gain showed that the sustainable biomass of pirarucu juveniles for intensive rearing in 1-m 3 net cages was approximately 29 kg. Fish length at the end of the trial, in relation to the reduced net cage space, was a limiting factor to obtain good biological indices