ABSTRACT

Hoplerythrinus unitaeniatus is popularly known as jeju or aimara. Widely distributed, occurs in many Central and South America basins, with the São Francisco River as type locality. In Brazil, the southernmost record of the species is the Uruguay River, Rio Grande do Sul State. This study reports the first record of H. unitaeniatus in the Patos Lagoon system, Guaiba hydrographic region, state of Rio Grande do Sul, Brazil. The capture occurred in a floodplain adjacent of the Sinos River near São Leopoldo city (29° 44' 14.04" S and 51° 05' 11.08" W). Two specimens were collected with drag net in May 2008. One specimen was anesthetized with 2-phenoxy-ethanol solution, fixed in formalin 10%, identified and included in the Museu de Ciências e Tecnologia da Pontífícia Universidade Católica do Rio Grande do Sul fish collection. The second specimen was kept alive in aquarium. After ten months it died of Lernaea cyprinacea (Crustacea, Copepoda) infestation. The presence of Lernaea and ease of captive breading of this species support the hypothesis that the collected fish escaped from regional fish farms. The accidental capture does not necessarily reflect a self-sustaining population, but shows the absence of supervision on breeding and marketing of non-native species, which may lead to a homogenized aquatic community.

The helminths belonging to the class Trematoda have great importance in ichthyoparasitology, and the subclass Digenea includes parasites with zoonotic potential. The family Heterophyidae is responsible for the heterophyiasis and, in Brazil, this disease is caused by the trematode genera Ascocotyle (Phagicola), commonly known as phagicolosis, both related to the fish-to-birds/mammals cycle. Clinostomum (belonging to the family Clinostomidae) has its larval stage in fish musculature and piscivorous birds as definitive hosts. It may parasitize humans accidentally, causing parasitic laryngopharyngitis and death by asphyxia. This study aims to quantify the presence of digenetic Heterophyidae and Clinostomidae parasites with zoonotic potential in fish from the Tramandaí River basin, in the state of Rio Grande do Sul, Brazil. The fish were purchased from fishermen from Terra de Areia/RS, from July 2016 to May 2017. The search for parasites was carried out by performing a necropsy on the fish. The digenetic parasites were preserved, stained and mounted on microscope slides for identification. Parasitological indices were calculated. Astyanax spp. Were positive for Ascocotyle whereas Geophagus brasiliensis was infected by Clinostomum sp. Therefore, the results suggest a risk of infection to the consumer population in the region.

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The introduction of non-native species in inland waters is one of the main threats for aquatic biodiversity. Introduced species may compete for resources, prey on native fauna, spread diseases and parasites. The channel catfish Ictalurus punctatus (Siluriformes, Ictaluridae) was first described by Rafinesque 1818 in the United States and is widely distributed in North America, south Canada and north-east Mexico. This species adapts easily to new environmental conditions, is tolerant to different habitats, and is grown easily in aquaculture, which turns it into a potential invader of natural aquatic environments. The introduction of I. punctatus occurs in Brazil since 1980, and this is the first record of its occurrence in the Rio dos Sinos basin, Brazil. A female adult catfish was captured during a survey in the main channel of the Rio dos Sinos (29º 44' 14.04" S and 51º 05' 11.08" W). Most probably the captured individual is an escapee from nearby aquaculture facilities.