Molecular identification of Austrodiplostomum sp., an eye parasite among farmed tambaqui in Amazonia.

Austrodiplostomum Szidat & Nani, 1951 is a genus of parasitic digenetic trematodes widely distributed in the Neotropical region. Infects a wide variety of species, families and requests for freshwater fish. We identify samples of Austrodiplostomum sp, based on metacercariae isolates from eyes of tambaqui (Colossoma macropomum), a fish of high commercial importance in Brazil, and widely consumed by the population of the northern region. The sequences obtained clustered with A. compactum. This is the first report of the occurrence of diplostomids in farmed tambaqui in Amazonia.

Growth performance, hematology parameters and Aeromonas hydrophila challenge of pirarucu (Arapaima gigas) in response to dietary protein levels.

The pirarucu (Arapaima gigas) is a fast-growing Amazonian species of high commercial value. The present study aimed to determine the dietary crude protein (CP) level to promote maximum zootechnical performance for pirarucu fingerlings and as their resistance to Aeromonas hydrophila, as well as evaluate their hematological parameters. Pirarucu fingerlings (2.4 ± 0.08 g, 6.8 ± 0.52 cm) were distributed in 18 tanks (140 L, 40 fish per tank, n = 3) and fed six experimental diets consisting of increasing levels of CP: 300, 400, 450, 500, 550 and 650 g kg-1 in a completely randomized design. Data were submitted to one-way ANOVA (p < 0.05) and the ideal CP level for weight gain was determined using polynomial regression analysis. The dietary CP levels were evaluated using a quadratic polynomial regression and the level of 595 g kg-1 was determined for the best weight gain. The hematocrit of fish fed 300 g kg-1 was higher than in the other groups. No mortalities were observed after the 15-day bacterial challenge; however, number of pirarucu with bacterial damage on the pirarucu caudal fin was higher in the group that was fed the diet with 300 g kg-1. A dietary protein level of 618 g kg-1 is therefore recommended for providing maximum weight gain and immunological resistance in pirarucu fingerlings weighing 2.4-112.5 g.

A fast and practical method for initial diagnosis of Piscinoodinium pillulare outbreaks: piscinootest / Um método rápido e prático para o diagnóstico inicial de surtos de Piscinoodinium pillulare: piscinootest

ABSTRACT: The dinoflagellate Piscinoodinium pillulare is a parasite with low parasitic specificity and unspecific geographical distribution. This research reported a simple and practical method - the principle of spontaneous sedimentation - to identify the presence of P. pillulare during massive infestations which does not require using precision equipment. Agitation in water of the gill arches of infested fish will elicit, after a period of rest, recording the accumulation of trophonts in the bottom of flasks. The method was applied during outbreaks of P. pillulare in tambaqui, Colossoma macropomum and matrinxã, Brycon amazonicus, in fish farms of the Amazon region and proved to be effective.

RESUMO: O dinoflagelado Piscinoodinium pillulare é um parasita com baixa especificidade parasitária e distribuição geográfica não específica. Este trabalho reporta um método simples e prático - o princípio da sedimentação espontânea - para identificar a presença de P. pillulare durante infestações maciças, que não requer o uso de equipamentos de precisão. A agitação em água dos arcos branquiais de peixes infestados permite, após um período de repouso, registrar o acúmulo de trofontes no fundo dos frascos. O método foi aplicado durante os surtos de P. pillulare em tambaqui, Colossoma macropomum e matrinxã, Brycon amazonicus, em pisciculturas comerciais da região Amazônica e provou ser eficaz.