José Eurico Possebon Cyrino

Antibiotic resistence of Aeromonas hydrophila isolated from Piaractus mesopotamicus (Holmberg, 1887) and Oreochromis niloticus (Linnaeus, 1758)

Um dos maiores problemas envolvendo o tratamento com antibioticos contra Aeromonas hydrophila isolada de peixes confinados e a rapida resistencia ao antibiotico desenvolvida pela bacteria. A atividade antimicrobiana de quimioterapeuticos em isolados a partir de pacu Piaractus mesopotamicus (Holmberg, 1887) e tilapia Oreochromis niloticus (Linnaeus, 1758) foi verificada pelo metodo de difusao de antibiotico em discos de Kirby-Bauer, sobre uma superficie de Agar Mueller-Hinton previamente inoculada com 100 µL de suspensao bacteriana. Apos o periodo de incubacao, os isolados de tilapia e pacu foram uniformemente resistentes a amoxicilina, ampicilina, lincomicina, novobiocina, oxacilina, penicilina e trimetoprim+sulfametoxazol. A cepa tipo para A. hydrophila apresentou resistencia as mesmas substâncias antimicrobianas e tambem contra a rifampicina; o isolado bacteriano de pacu foi a unica linhagem resistente a tetraciclina. Isolados de pacu e tilapia apresentaram resistencia intermediaria frente a eritromicina. O uso de medicamentos em pisciculturas comerciais no Brasil pode favorecer o desenvolvimento de linhagens bacterianas resistentes em especies de peixes nativos, como ja observado em especies exoticas comercialmente produzidas ha mais tempo.

A piscicultura e o ambiente: o uso de alimentos ambientalmente corretos em piscicultura

Although fish nutrition science is far from establishing general standards of nutritional requirements, the need for developing low impact feeds has long been included in the agenda of aquacultures international scientific and business communities of. Not only is absolutely possible to formulate environmental friendly feeds, as it is necessary modeling the formulation of these feeds. However, it is necessary higher accuracy to develop species-specific formulations, considering interactions of the biology and nutritional physiology of the species with the feedstuffs and variations of abiotic environment. The knowledge on more than 200 species of commercially farmed fish is still incipient and fish production systems, in their most varied farming conditions, are set up in every possible ecological conditions. In this scenario, producing environmental friendly feeds is if not impossible, at least very, very difficult, depending on coordinated and positive action of producers, industry, regulatory agencies, and institutions of higher education and research to define the parameters needed to achieve this goal.

Relação energia: proteína na nutrição do tucunaré

O objetivo deste estudo foi avaliar o efeito da relacao energia:proteina no desempenho e composicao corporal do tucunare. Para tanto, 196 alevinos de tucunares (Cichla sp.), condicionados a aceitar alimentos secos, com peso medio vivo de 10 g, foram estocados em gaiolas de tela de volume igual a 25 L, alojadas em 16 caixas de cimento amianto com volume de 500 L, instaladas em uma estufa e abastecidas por um sistema fechado de recirculacao de agua. Os peixes foram alimentados ad libitum com racao seca em duas refeicoes diarias, por um periodo de 65 dias com quatro racoes isoenergeticas (3.500 kcal de ED kg-1 de racao), com niveis de proteina bruta de 41%, 37%, 33% e 30% de forma a obter uma relacao ED:PB de 8, 9, 10 e 11 kcal de ED g-1 de PB, estabelecendo-se um delineamento experimental inteiramente casualizado com 4 tratamentos e 4 repeticoes. No inicio do experimento um lote de peixes foi sacrificado para determinacao dos teores corporais de proteina, gordura, agua e materia mineral. No final do periodo experimental, foram sacrificados lotes de peixes de cada tratamento para nova analise de composicao corporal. Os dados obtidos foram submetidos a analise de variância utilizando-se do software SAS, e aplicando-se regressao polinomial para avaliar o efeito das relacoes ED:PB nas variaveis analisadas ao nivel de 5% de probabilidade. Os resultados permitem inferir que a exigencia nutricional do tucunare pode ser suprida por uma racao contendo entre 8 e 9 kcal de ED g-1 de PB, ou seja, 37 a 41% de PB e 3.500 kcal de ED kg-1 de alimento.

Produção da tilápia vermelha da Flórida em tanques-rede

A producao de peixes em tanques-rede no Brasil tem aumentado nas ultimas decadas. O baixo investimento inicial e o potencial hidrico representado pela enorme quantidade de agua represada em nosso Pais tem atraido o interesse de empresarios para essa atividade. O objetivo desse trabalho foi gerar informacoes sobre o efeito da densidade de estocagem no crescimento e produtividade da tilapia vermelha da Florida criadas em tanques-rede. Foram instalados doze tanques-rede de 5 m3, numa represa de 1 ha, e estocados com 25, 50, 75 e 100 tilapias vermelhas da Florida revertidas por m3. Os peixes foram alimentados com racoes extrusadas comerciais contendo 32 e 28% PB por 253 dias. As temperaturas maxima, minima e media da agua foram 32,2, 16,0 e 23,9 C, respectivamente. Tambem foram monitorados a condutividade (58 mS/cm2), alcalinidade total (28 mg/L), amonia nao ionizada (0,26 mg/L), nitrito (0,02 mg/L), oxigenio dissolvido (4,1 mg/L) e transparencia da agua (37 cm). Foram determinados o peso medio final (279,54g), comprimento padrao medio final (18,72cm), fator de condicao (4,12), conversao alimentar aparente (3,15), taxa de sobrevivencia (96,9%), ganho de peso diario (0,92g), taxa de crescimento especifico (0,70%) e coeficientes de variacao do peso (0,357%), do comprimento padrao (0,136%) e do fator de condicao (0,136%). Nao foram observadas diferencas significativas (P>0,05) entre as densidades de estocagem testadas nesses parâmetros. A densidade de estocagem de 100 peixes/m3 proporcionou a maior biomassa por m3 (P<0,001).

Suplementação de vitamina C em rações para reversão sexual da tilápia do Nilo

The effects of vitamin C supplementation (0; 50; 100; 200; 400; 600; 800; 1,000 mg kg-1 of diet) on diets for sex reversal of the Nile tilapia, Oreochromis niloticus, were evaluated on groups of 600 larvae stocked in 0.08 m3 hapas and fed for 30 days with hormone-treated feeds containing different supplementation levels (n=3). Weight gain and total length increment were evaluated after days 0, 10, 20 and 30. Survival rate (S%) and sex reversal rate (SR%) were determined at the end of the experimental period. Weight gain and total length became significantly different only after day 20 (P<0.0001). Best results for weight gain were attained with dietary vitamin C levels above 800 mg kg-1, while the best results for growth in length were attained with dietary vitamin C levels above 400 mg kg-1. Levels of supplementation higher than 200 mg kg-1 did not lead to better survival rates. SR% values were not significantly affected by vitamin C supplementation of sex reversal diets (P<0.9993). Optimal values for vitamin C supplementation of sex reversal diets for the Nile tilapia, derived from polinomial regression analysis procedures, were: weight gain 859.5 mg; growth in length 765.0 mg, and for survival rate 685.7 mg.

Diversity and associations between coastal habitats and anurans in southernmost Brazil

This study aimed to verify the relationship between habitat and the composition of anuran species in dune and restinga habitats in southernmost Brazil. The habitats were sampled between April 2009 and March 2010 using pitfalls with drift fence. We have captured 13,508 individuals of 12 anuran species. Species richness was lower in the dunes and dominance was higher in the resting. Apparently the less complex plant cover, water availability, and wide daily thermal variation in dunes act as an environmental filter for frogs. This hypothesis is reinforced by the fact that the most abundant species (Physalaemus biligonigerus and Odonthoprynus maisuma) bury themselves in the sand, minimizing these environmental stresses. Despite being in the Pampa biome, the studied community was more similar to those of coastal restinga environment of southeast Brazil than with other of the Pampa biome. The number of recorded species is similar to those observed in other open habitats in Brazil, showing the importance of adjacent ones to the shoreline for the maintenance of the diversity of anurans in southernmost Brazil.This study aimed to verify the relationship between habitat and the composition of anuran species in dune and restinga habitats in southernmost Brazil. The habitats were sampled between April 2009 and March 2010 using pitfalls with drift fence. We have captured 13,508 individuals of 12 anuran species. Species richness was lower in the dunes and dominance was higher in the resting. Apparently the less complex plant cover, water availability, and wide daily thermal variation in dunes act as an environmental filter for frogs. This hypothesis is reinforced by the fact that the most abundant species (Physalaemus biligonigerus and Odonthoprynus maisuma) bury themselves in the sand, minimizing these environmental stresses. Despite being in the Pampa biome, the studied community was more similar to those of coastal restinga environment of southeast Brazil than with other of the Pampa biome. The number of recorded species is similar to those observed in other open habitats in Brazil, showing the importance of adjacent ones to the shoreline for the maintenance of the diversity of anurans in southernmost Brazil.

Feed training of peacock bass (Cichla sp.)

The Amazonian cichlid peacock bass (Cichla sp.) is a highly marketable food and sport fish, therefore a suitable species for aquaculture. However, because of its piscivorous feeding preferences, the species does not accept dry feeds voluntarily, turning its intensive culture difficult and costly. This study aimed to wean fingerling peacock bass from inert moist food to dry diets. In a first experiment, 1,134 fingerlings weighting 0.27 g were divided in two 0.37 m3 hapas and fed ground fish flesh with 35% success. Then, 1.3 g fish were pooled, stocked in six 25 L cages and fed two pellet sequences with 80%, 60%, 40%, 20% and 0% ground fish flesh (GFF). One sequence was flavored with 10% krill meal (Euphausia sp.). Training success of fish fed the GFF-00 diet flavored with krill reached 12%a compared to 11.6%a (p < 0.05) for diets without krill meal. A second experiment was set up with 969, 1.5 g fish, trained with GFF with 39.8% success. After the feed training period, 2.2 g fish were then fed a sequence of moist pellets containing 80%, 60% and 45% GFF. Fish trained to feed on moist pellets with 45% ground fish were pooled and stocked into nine 25 L cages. Fish were weaned to dry pellets without ground fish flesh (GFF-00) using three diet sequences: 1) dry pellets; 2) moist pellets; and 3) dry pellets flavored with 4% cod liver oil; all three diets contained 30, 10 and 0% GFF. The three sequences yielded, respectively 30.8%a, 23.6%a, and 24.7%a (p < 0.05) fish feeding on GFF-00. There were no apparent beneficial effects of increasing moisture or addition of cod liver oil as flavor enhancers in the weaning diets. This study revealed the feasibility of training peacock bass to accept dry pellets, but feeding young fish ground fish flesh seemed to be a major bottleneck in improving feed training success.

Protein and energy retention by juvenile largemouth bass Micropterus salmoides.

To determine dietary protein and energy retention of juvenile largemouth bass one thousand, three hundred and fifty feed-conditioned fish (average weight 14.46 ± 0.81 g) were stocked in 60-L cages set up in 1,000 L containers, and fed for 64 days with a dry, extruded feed containing varying levels of crude protein - CP (34, 38, 42, 46, 50 and 54%) and energy (3,600 to 4,100 kcal kg-1 feed, with increases of 125 kcal kg-1). The trial was set up in a totally randomized 6 x 5 factorial design (n=3). Data on weight gain, daily feed consumption, hepatosomatic index, viscerosomatic index, nutrient protein, energy retention, liver glycogen and visceral fat were evaluated. There were no interaction effects (P > 0.05) between feed energy and protein levels in respect to all evaluated parameters. Best performance was attained with levels of 42% CP and 3,850 kcal kg-1 in the diets, a condition which resulted in higher levels of liver glycogen (P < 0.0442) and higher hepatosomatic indexes (P < 0.0001) usually when diets presented less than 30% starch. Higher levels of dietary lipid induced significant increases in whole body lipids considering dietary energy (Pxa0<xa00.0001), and this also induced higher deposition of visceral fat for pooled means of dietary protein (P < 0.0001) and energy (P < 0.0021) contents. These results will help understanding the nutritional energetics of carnivorous fish, increasing the feasibility of their intensive production.

Attractants in plant protein-based diets for the carnivorous largemouth bass Micropterus salmoides

A adicao de estimulantes pode melhorar a aceitabilidade de dietas artificiais por pos-larvas e alevinos de peixes carnivoros, aumentando a ingestao de alimentos nao palataveis e a taxa de crescimento, reduzindo o tempo de alimentacao e perdas alimentares. Investigou-se o uso de atrativos alimentares em dietas formuladas exclusivamente a base de proteina de origem vegetal (PV), e seus efeitos no desempenho de alevinos do carnivoro black bass, Micropterus salmoides, condicionados a aceitar racao seca. Novecentos juvenis (26,54 ± 1,53 g) foram estocados em 60 aquarios de polietileno de 90 L (15 peixes por aquario), em delineamento experimental totalmente ao acaso (n=3), e alimentados ad libitum em duas refeicoes diarias (7h00 e 17h00), durante 13 dias, com uma dieta basal (100% PV) contendo seis niveis de proteina soluvel de peixe - PSP (0,5, 1,0, 1,5, 2,0, 2,5 e 3,0%); Fisharom®- FA (0,02, 0,04, 0,06, 0,08, 0,10 e 0,12%); silagem de peixe - SP (1,0, 2,0, 3,0, 4,0, 5,0 e 6,0%); um controle positivo (10% de farinha de peixe) e um controle negativo (dieta basal sem atrativos). Os peixes alimentados com a dieta contendo FA 0,02% apresentaram melhor taxa de crescimento, ganho de peso e conversao alimentar. Os peixes alimentados com dietas contendo SP como atrativo apresentaram os piores resultados de desempenho.

Desempenho da tilápia nilótica Oreochromis niloticus (L.) em gaiolas de pequeno volume

To determine the carrying capacity and overall performance of the Nile tilapia Oreochromis niloticus (L.) in small volume cages, 5,850 sexually inverted fingerlings, averaging 18.85 g of live weight, were stocked in 1.3 m3 cages, at densities of 75, 150, 300, and 600 fish/m3 (T75; T150; T300, and T600). The 196-day long trial was set up in a totally randomized design, with 4 treatments and 3 replicates. Cages were set up in a 4-ha, 2 m average depth reservoir. Twenty percent (20%) of each cage stock were weighed and measured every 30 d to determine growth rate as weight gain (WG), and feed conversion rate (FCR). Fish were fed twice-a-day (09:00 and 17:00 h) an extruded, floating, 28% crude protein commercial diet. Feed consumption, mortality and water temperature were recorded at feeding time, and pH, dissolved oxygen (DO) and water transparency were recorded monthly. The first evaluation (30-d) showed FCR values between 0.68 and 2.40:1, and WG between 11.19 and 21.52 g. Best FCR values were recorded for T600. However, the stock could not repeat or maintain the initial performance level, and final results showed: FCR = 6.31:1 and WG = 71.52 g for T75; FCR = 4.08:1 and WG = 65.14 g for T150; FCR = 3.57:1 and WG = 59.60 g for T300; and FCR = 2.96:1 and WG = 69.17 g for T600. The best WG result was attained by T600, which was not significantly different of T75 (P<0.01). The FCR was better for T600 than for T75. The performance of both T150 and T300 was inferior to T600 and T75. Compared to literature data, the performance of Nile tilapia in this trial was very poor. Low cage effective depth (0.85 cm), causing thermal and brightness stress, poor quality of commercial feed and low sex reversal rate of fish stock could explain the unsatisfactory results here obtained.