ABSTRACT
The objective of this study was to investigate the parasites occurrences and to determine the rates of infestation/parasitic infection in juvenile Arapaima gigas from seven fish farms in the state of Amazonas, relating to the characteristics of these fish farms. Of the 70 A. gigas evaluated, 43 were infested/infected, with a total of 133 parasites collected. Three fish farms (2, 4, 6) showed the highest levels of prevalence of parasites (100%, 70%, 70%), mean intensity (4.1±2.6, 8.1±9.2, and 2.1±1.3), and mean abundance (4.1±2.6, 5.7±8.1, and 1.5±1.5), respectively. Prevalence ranged from 30% to 100%, mean intensity from 1.0 to 8.1 and mean abundance from 0.3 to 5.7. Monogenea, Digenea, Nematoda (Hysterothylacium sp. and Spirocamallanus sp.) and Acanthocephala (Neoechinorhynchus sp. and Polyacanthorhynchus sp.) were identified. The parasites Hysterothylacium sp. and Neoechinorhynchus sp. were the most prevalent parasites with 31.43% and 15.71%, respectively. The fish presented negative allometry in growth and constant condition factor. Measures to prevent and control the parasitic diseases diagnosed are discussed as well prophylactic practices that contribute to the biosecurity of the farms.
Subject(s)
Acanthocephala , Ascaridoidea , Fish Diseases , Parasites , Trematoda , Animals , Fisheries , Brazil/epidemiology , Fishes/parasitology , Fish Diseases/epidemiology , Fish Diseases/parasitologyABSTRACT
Foi estudada a fauna de metazoários parasitos de Pygocentrus nattereri capturadas no lago Piranha, durante as fases do ciclo hidrológico do ano de 2007. Foi verificada a relação entre o fator de condição e a ocorrência de parasitos, e também a viabilidade da utilização da fauna parasitária de P. nattereri como bioindicadora da saúde do ambiente. Foram coletados monogenóideos das espécies Amphithecium microphalum, Amphitecium brachycirrum, Amphitecium calycinum, Amphithecium catalaoensis, Amphithecium junki, Pithanothecium amazonensis e Rhinoxenus piranhus, o nematóide Procamallanus inopinatus, copépodos da espécie Miracetyma sp. e o isópoda Anphira branchialis. Não houve correlação significativa entre a ocorrência dos parasitos com o fator de condição dos peixes. Houve variações significativas entre os índices parasitários nos diferentes períodos do ciclo hidrológico e P. nattereri satisfez os requisitos descritos na literatura para selecionar um peixe hospedeiro e sua parasitofauna como bioindicadora.
The metazoan parasitic fauna of Pygocentrus nattereri collected in different phases of hydrologic cycle of Piranha lake was studied during the year of 2007. The study area is located in gas pipeline Coari-Manaus construction zone, near the municipality of Manacapuru-Am. The relationship between condition factor and parasite occurrence and the viability of use the parasitic fauna as an environmental bio-indicator were verified. The following Monogenoidea were collected: Amphithecium microphalum, Amphitecium brachycirrum, Amphitecium calycinum, Amphithecium catalaoensis, Amphithecium junki, Pithanothecium amazonensis e Rhinoxenus piranhus, as well as the nematode Procamallanus inopinatus, the copepod Miracetyma sp. and the isopod Anphira branchialis. There was not significant correlation between the parasite occurrence and the condition factor. There were significant variances in the parasitic index according to the different periods of hydrologic cycle and P. nattereri has achieved the conditions described in the literature to be select a fish-host and his parasite fauna as biomonitor.
