ABSTRACT. The aim of this study was to evaluate the inclusion of different levels of soybean meal in pirarucu’s diet. 200 pirarucu juveniles (152.15 ± 0.8 g) were distributed in 20 polyethylene tanks with a continuous water flow system. A completely randomized experimental design was used, with five treatments (n = 4) containing 0, 10, 20, 30 and 40% of soybean meal inclusion levels. Growth performance was measured as specific growth rate, feed conversion, weight gain and survival. Body composition, protein retention rate and histopathological changes in the intestine were analyzed. The different treatments did not affect weight gain, specific growth rate and survival. The body composition of the fish was affected by treatments for ash and ether extract and the IHS was also affected. The diet with 40% soybean meal compromised feed conversion rate. Additionally, the distal intestine of fish fed with the same diet showed a reduction in the height of mucosal folds and a loss of supranuclear vacuolation in enterocytes. Based on these results, the inclusion of up to 30% of soybean meal in the diet of juvenile pirarucu is possible without negative effects on performance and enteric morphology. ABSTRACT pirarucus s 152.15 15215 152 15 (152.1 08 0 8 0. g 2 system used n 4 10 3 40 survival analyzed Additionally enterocytes results morphology 152.1 1521 1 (152. 152. (152 (15 (1 (

Resumo O parasitismo intenso por tricodinídeos está frequentemente relacionado à doença grave em fazendas de peixes. Neste estudo, espécies de tricodinídeos das brânquias e da pele de tilápias do Nilo (Oreochromis niloticus) cultivadas na região centro-oeste do Brasil (estado de Goiás) foram caracterizadas morfologicamente. As lâminas secas foram preparadas a partir dos parasitas e impregnadas com nitrato de prata (2%). As características morfométricas foram determinadas e desenhos esquemáticos dos dentículos foram confeccionados com fotomicrografias produzidas a partir das lâminas. Sete espécies de ectoparasitos tricodinídeos (Protozoa: Ciliophora: Trichodinidae) foram encontradas parasitando as brânquias: quatro do gênero Trichodina Ehrenberg, 1838; um de Tripartiella Lom, 1959; um de Paratrichodina Lom, 1963; e um de Trichodinella Ṧrámek-Huṧek, 1953. Na superfície do corpo, três espécimes do gênero Trichodina foram identificados. Este estudo apresenta novos registros geográficos de tricodinídeos no Brasil, confirmando que Trichodina centrostrigeata, Trichodina compacta, Trichodina heterodentata, Paratrichodina africana e Tripartiella orthodens estão amplamente distribuídas mundialmente. Adicionalmente, é apresentado o primeiro registro do gênero Trichodinella no Brasil.

Abstract Massive occurrence of trichodinids is frequently accompanied by serious disease in fish farms. In this study, trichodinid species from the gills and skin of Nile tilapia (Oreochromis niloticus) farmed in the central-western region of Brazil (state of Goiás) were morphologically characterized. Dried slides were prepared from the parasites and were impregnated with silver nitrate (2%). Morphometric characteristics were determined and schematic drawings of the denticles were made using photomicrographs produced from the slides. Seven species of trichodinid ectoparasites (Protozoa: Ciliophora: Trichodinidae) were found parasitizing the gills: four of the genus Trichodina Ehrenberg, 1838; one of Tripartiella Lom, 1959; one of Paratrichodina Lom, 1963; and one of Trichodinella Ṧrámek-Huṧek, 1953. On the body surface, three specimens of the genus Trichodina were identified. This study presents new geographical records of trichodinids in Brazil, thus confirming that Trichodina centrostrigeata, Trichodina compacta, Trichodina heterodentata, Paratrichodina africana and Tripartiella orthodens are widely distributed worldwide. Additionally, the first record of the genus Trichodinella in Brazil is presented.