First report of Trichodinella and new geographical records of trichodinids in Nile tilapia (Oreochromis niloticus) farmed in Brazil

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. ResumoO 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.

First record of Trichodina heterodentata (Ciliophora: Trichodinidae) in banded knifefish Gymnotus carapo (Gymnotidae) cultured in Brazil

“…Ciliated trichodinids (Mobilida) are among the main etiological agents of mortality in farmed fish. Trichodinids are of great importance in fish cultivation, especially when the environment favors their reproduction, in which case severe infestations can damage the gills and skin of the fish, making them susceptible to respiratory problems and secondary infections (Zanolo & Yamamura, 2006;Valladão et al, 2016;Rodrigues et al, 2019). In addition, the banded knifefish included in this study were farmed at a high stocking density (90-110 fish/500 L tank), which was well above the recommended stocking density for this species (approximately 100 fish for every 1,000 L of water, Ishikawa et al, 2017).…”

A global review of problematic and pathogenic parasites of farmed tilapia

“…niloticus in Egypt and an unidentified tilapia in Africa has been translocated on O . niloticus and its hybrids to Brazil, 103,105,116–118 Mexico, 103 China, 119 Egypt 120 and Argentina 113 . It is possible that the record of P .…”

“…Trichodinella epizootica (Raabe, 1950) and an undescribed Trichodinella are recorded from the gills of farmed O . niloticus from Mexico, 113 Egypt, 120 Kenya, 17 Brazil 118 and Uganda, 17 and from O . mossambicus and C .…”

“…mossambicus from Taiwan Province of China, 122 O . niloticus and hybrids from Vietnam, 67 the Philippines, 16,123 Brazil, 118,124 Mexico 103 and China 119 and C . zillii from the Philippines 16,125 …”

Enterogyrus spp. (Monogenea: Ancyrocephalinae) and Aeromonas jandaei co‐infection associated with high mortality following transport stress in cultured Nile tilapia

“…(Oh et al., 2020), Francisella orientalis (Sebastião et al., 2017), Lactococcus garvieae (Evans et al., 2009), and Vibrio spp. (Sumithra et al., 2019), as well as parasitic diseases caused mainly by protozoans (Martins et al., 2015; Rodrigues et al., 2019), monogenetic (Abdel‐Latif & Khafaga, 2020) and digenetic trematodes (Abdel‐Latif et al., 2020). Co‐infection by these pathogens, either simultaneously or as a secondary concurrent infection, potentiates the pathogenic effects and leads to serious negative consequences for the host (Abdel‐Latif et al., 2020).…”