This study investigated the parasite communities of wild Acestrorhynchus falcatus and Acestrorhynchus falcirostris populations living in sympatry in Brazilian Amazon. In these two hosts, a total of 12 parasite species e 1-9 parasite species were found per fish, and 10 of these species are metazoans. Eight species of parasites were common to both host species and four of them exhibited differences in abundance and/or prevalence. Parasite communities of the hosts were taxonomically similar (83%) and composed of both ectoparasites and endoparasites, and characterized by high prevalence and high abundance of endoparasites and an aggregated dispersion pattern. For A. falcirostris, the dominant parasite was Ichthyophthirius multifiliis, and for A. falcatus, it was Piscinoodinium pillulare. Shannon diversity and Berger-Parker dominance were similar for both hosts, while the parasites species richness and evenness showed differences influenced by the ectoparasites species. These two populations of hosts that inhabited the same geographical area had different sizes, but were exposed to the same infective stages, and acquired qualitatively and quantitatively similar endoparasites community, thus indicating that the amounts and types of prey congeneric that they were eating were similar. Therefore, the overlap in the same occurrence area play an important role in the parasite communities to these phylogenetically related hosts.

This study was the first investigation of communities and infracommunities of parasites of Hemibrycon surinamensis. All the fish collected in a tributary of the Amazon river were parasitized by one or more parasite species. The Brillouin diversity index (HB) was 0.46 ± 0.28 and the mean species richness was 3.5 ± 1.2 parasites per host. A total of 14,734 parasites were collected, including Ichthyophthirius multifiliis and Piscinoodinium pillulare (Protozoa); Jainus hexops and Tereancistrum sp. (Monogenoidea); Ergasilus turucuyus and Argulus sp. (Crustacea); metacercariae of Derogenidae gen. sp.; metacercariae and adults of Genarchella genarchella (Digenea); and Cucullanus larvae and Contracaecum larvae (Nematoda). The dominant parasite was I. multifiliis, followed by P. pillulare. The parasites showed aggregated dispersion, except for E. turucuyus, which had random dispersion. The condition factor (Kn) indicated that the parasitism levels had not affected host body condition. The high levels of infection observed were due to host behavior, and this was discussed. This was the first report of I. multifiliis, P. pillulare, Argulus sp., E. turucuyus, G. genarchella, J. hexops and Tereancistrum sp. in H. surinamensis, and it expanded the occurrence of E. turucuyus and G. genarchella to the eastern Amazon region.

ABSTRACT. The present study provides the first investigation on the ecological aspects of the parasites M. lippincottianus from the Amazonian basin, as well as the parasite-host relationship. 76 out of the examined fish (98.7%) were parasitized by at least one species of parasites.

The hematological and biochemical responses of pirarucu fingerlings (Arapaima gigas) fed with diets containing different concentrations of a glucomannan product derived from yeast and algae were evaluated in order to ascertain the effect of these diets on fish physiology. Four treatments were conducted, with three replications, with 12 fish in each tank. The product evaluated (MycosorbA+(r)) was incorporated into the commercial diet, at four concentrations: 0, 1, 2 and 4 g.kg-1, called M0%, M0.1%, M0.2% and M0.4%, respectively. After 45 days of feeding, blood samples from six fish in each replicate were collected to perform the analyses. Their weight and length were determined to calculate the condition factor and weight gain, but no differences (P > 0.05) were observed among the treatments. No changes to the hematocrit, hemoglobin or erythrocyte levels or to the hematimetric indices of the pirarucus were observed. The glucose and triglyceride levels of the pirarucus in the M0.1% and M0.2% groups were significantly lower than those of the M0% group. The M0.2% group showed higher albumin levels (P < 0.05) than M0% and M0.4%. The M0.4% group showed a total cholesterol level that was significantly higher than in all other treatments. MycosorbA+(r) contributed towards increasing the levels of defense cells in A. gigas. It would be possible to use this product at concentrations of between 0.1% and 0.2%, given that they increase the levels of some defense cells and plasma albumin concentrations, without changes to hematological parameters, cholesterol and triglyceride plasma levels or condition factor.

This study investigated the parasites fauna of four freshwater ornamental fish species in aquarium shops of Macapá, Amapá State, in addition to survey the commercialized fish species and sanitary conditions of aquarium shops. Different native and non-native ornamental fish species were found in aquarium shops, mainly Poecilidae. We examined 30 specimens of Xiphophorus maculatus, 30 Danio rerio, 30 Paracheirodon axelrodi, and 30 Corydoras ephippifer for parasites. Of the 120 fish examined, 22.5% were parasitized by one or more species and a total of 438 parasites were collected and identified. Parasites such as: Ichthyophthirius multifiliis, Monogenea, undermined Digenea metacercariae, Acanthostomum sp. metacercariae, Camallanus spp., Bothriocephalus acheilognathi and Echinorhynchus sp. infected the hosts examined. Endoparasites in the larval stage showed the greatest diversity and Camallanus spp. was found in all hosts species examined. Paracheirodon axelrodi (43.3%) was the most parasitized host, while C. ephippifer (6.7%) was the least parasitized. Despite the low ectoparasites level, six species of endoparasites was observed, demonstrating that prophylactic and quarantine procedures were not fully adequate. Therefore, failures in prophylactic procedures on any link in the production industry of ornamental fish may cause parasite transmission to ornamental fish captured in different environments and localities.

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