The Phylum Protozoa brings together several organisms evolutionarily different that may act as ecto or endoparasites of fishes over the world being responsible for diseases, which, in turn, may lead to economical and social impacts in different countries. Apart from the recent advances for the diagnosis of fish diseases in Brazil, little is known on the protozoan parasites and their relationship with environment and host. This revision presents the most important protozoan parasites found in farmed fish from Brazil, not only with emphasis on its diagnosis, biology, transmission and host-parasite relationship, but also on some information that may be useful to researchers in determining the correct diagnosis in fish farms.Keywords: Fish parasites, disease, ciliate, dinoflagellate, pathogenicity. ResumoO filo Protozoa reúne diversos organismos evolutivamente distintos que podem atuar como ecto ou endoparasitos de peixes em todo o mundo, sendo responsáveis por doenças as quais, por sua vez, podem ocasionar impactos econômico e social nos diferentes países. Apesar dos recentes avanços no campo de diagnóstico de doenças em peixes no Brasil, ainda pouco se conhece sobre a fauna de protozoários parasitos de peixes e suas relações com o ambiente e hospedeiro. Esta revisão apresenta os mais importantes protozoários parasitos encontrados em peixes cultivados no Brasil, não apenas com ênfase no seu diagnóstico, biologia, transmissão e relação hospedeiro-parasito, mas também algumas informações que podem ser úteis para pesquisadores para o correto diagnóstico em pisciculturas.Palavras-chave: Parasitos de peixes, enfermidade, ciliado, dinoflagelado, patogenicidade.

This study characterises morphologically Trichodina heterodentata Duncan, 1977 from channel catfish, Ictalurus punctatus (Rafinesque, 1818) in the State of Santa Catarina, Brazil. Body and gill smears were air-dried at room temperature, impregnated with silver nitrate and/or stained with Giemsa. Ten characteristics were selected to compare the present material with other morphological characterisations of T. heterodentata. Prevalence rate was 100%, mean intensity 89,333.70 (3,125 to 299,100 parasites per host). Trichodina heterodentata was considered medium-sized trichodinid with mean body diameter 59.4 ± 8.5 µm, denticulate ring 38.5 ± 4.5 µm, adhesive disc 60.2 ± 6.7 µm diameter and 24.4 ± 1.6 denticles. In relation to previous reports of T. heterodentata this material resembles in 90% of the analysed characters. This work confirms the biometrical variation that exists in the different populations of T. heterodentata. A list of hosts and comparative measurements of T. heterodentata are presented and the channel catfish is considered a new host.Keywords: channel catfish, trichodinid, Trichodina heterodentata, morphology. Trichodina heterodentata foi considerado um tricodinídeo de tamanho médio com a média do diâmetro do corpo de 59,4 ± 8.5 µm, anel denticulado 38,5 ± 4,5 µm, disco adesivo 60,2 ± 6,7 µm de diâmetro e 24,4 ± 1,6 dentículos. Em relação a registros prévios de T. heterodentata, 90% das características foram semelhantes. Este trabalho confirma a variação biométrica que existe em diferentes populações de T. heterodentata. Uma lista de hospedeiros e medidas comparativas de T. heterodentata são apresentadas e o bagre-do-canal considerado um novo hospedeiro. Primeiro registro dePalavras-chave: bagre do canal, tricodinídeo, Trichodina heterodentata, morfologia.

Representatives of Ligophorus Euzet et Suriano, 1977 were found on the gills of Mugil liza Valenciennes caught in southern Brazil. They were identified as Ligophorus uruguayense Failla Siquier et Ostrowski de Núñez, 2009 and Ligophorus saladensis Marcotegui et Martorelli, 2009, even though specific identification proved to be difficult due to inconsistencies in some diagnostic features reported for these two species. Therefore, a combined morphological and molecular approach was used to critically review the validity of these species, by means of phase contrast and confocal fluorescence microscopical examination of sclerotised hard parts, and assessing the genetic divergence between L. saladensis, L. uruguayense and their congeners using rDNA sequences. The main morphological differences between the two species relate to the shape of the accessory piece of the penis and the median process of the ventral bar. The accessory piece in L. uruguayense is shorter than in L. saladensis, has a cylindrical, convex upper lobe and straight lower lobe (vs with the distal tip of the lower lobe turning away from the upper lobe in the latter species). The ventral bar has a V-shaped anterior median part in L. uruguayense (vs U-shaped in L. saladensis). The two species are suggested to be part of a species complex together with L. mediterraneus Sarabeev, Balbuena et Euzet, 2005. We recommend to generalise such comparative assessment of species of Ligophorus for a reliable picture of the diversity and diversification mechanisms within the genus, and to make full use of its potential as an additional marker for mullet taxonomy and systematics.

In the present work Trichodina reticulata and T. nobilis (Ciliophora: Trichodinidae) are morphologically characterised from ornamental freshwater fish culture in the State of Santa Catarina, Brazil. The prevalence of infection and a list of comparative measurements are discussed. We examined "southern platyfish" Xiphophorus maculatus (n = 35), "goldfish" Carassius auratus (n = 31), "guppy" Poecilia reticulata (n = 20), "sailfin molly" Poecilia latipinna (n = 6), "beta" Betta splendens (n = 2) and "spotted headstander" Chilodus punctatus (n = 1). After being anesthetised in a benzocaine solution, fishes were examined for parasitological evaluation. A total of 51.57% fishes were parasitised by Trichodina spp. Carassius auratus was the most parasitised species, followed by X. maculatus and P. reticulata. Beta splendens, C. punctatus and P. latipinna were not parasitised by any trichodinid species. Two species of Trichodina were collected from the skin of fish: T. nobilis was found in C. auratus, P. reticulata and X. maculatus and T. reticulata was only observed in C. auratus. The importance of adequate handling in ornamental fish culture are also discussed.Keywords: ornamental fish, parasites, Trichodina nobilis, Trichodina reticulate. Trichodina nobilis Chen, 1963 e Trichodina reticulata Hirschmann et Partsch, 1955 de peixes ornamentais de água doce no Brasil ResumoNo presente trabalho Trichodina reticulata e T. nobilis (Ciliophora: Trichodinidae) de peixes ornamentais de água doce cultivados no estado de Santa Catarina, Brasil são caracterizadas morfologicamente. A prevalência de infecção e uma lista comparative de medidas são discutidas. Foram examinados "platis" Xiphophorus maculatus (n = 35), "kinguios" Carassius auratus (n = 31), "guppys" Poecilia reticulata (n = 20), "molinésias" Poecilia latipinna (n = 6), "betas" Betta splendens (n = 2) e "espada" Chilodus punctatus (n = 1). Após a anestesia com solução de benzocaína, os peixes foram submetidos à avaliação parasitológca. Um total de 51,57% peixes estavam parasitados por Trichodina spp. Carassius auratus foi a espécie mais parasitada, seguida por X. maculatus e P. reticulata. Beta splendens, C. punctatus e P. latipinna não estavam parasitados por tricodinídeos. Duas species de Trichodina foram coletadas da superfície corporal dos peixes: T. nobilis foi encontrada em C. auratus, P. reticulata e X. maculatus e T. reticulata foi observada apenas em C. auratus. A importância do manejo adequado em cultivos de peixes ornamentais também foi discutida.

Family Trichodinidae comprises ciliate protozoa distributed worldwide; they are considered some of the main parasitological agents infecting cultivated fish. However, the trichodinidae parasitizing important fish species cultured in Brazil are unknown, and more taxonomic studies on this group of parasites are required. This research morphologically characterizes Trichodina colisae Asmat & Sultana, (2005) of pacu (Piaractus mesopotamicus) and patinga hybrid (P. mesopotamicus × P. brachypomus) cultivated in the central and southeast regions of the country. Fresh assemblies were made from mucus scraped from the skin, fins and gills, fixed with methanol and, subsequently, impregnated with silver nitrate and stained with Giemsa for assessment under light microscopy. This research reports not only the second occurrence of T. colisae in the world, but also its first occurrence in South America.

ABSTRACT. The orange disease is considered the main parasitosis in Perna perna mussel. It is caused by a complex life cycle bucephalid, involving three hosts, among them mollusks and fishes. With the aim of contributing to the knowledge of orange disease in mussel culture, the parasite life cycle was investigated. Experimental studies and monthly samples in the study area allowed the identification and characterization of the Bucephalus margaritae life cycle. Larvae and adults of B. margaritae were fixed in 5% formaldehyde, stained with Gomori's trichrome, clarified in creosote and mounted in Canada balsam.

ABSTRACT. Parasitological indexes of Austrodiplostomum compactum (Digenea, Diplostomidae) in fishes from the Paraná River, Presidente Epitácio region, state of São Paulo, Brazil, and their relationship with climate and water quality are evaluated. Fifty-one specimens of Plagioscion squamosissimus, 39 Geophagus surinamensis, 27 Hoplias malabaricus and 23 Cichla sp. were collected between June 2007 and June 2008. Water quality and rainfall indexes were measured monthly. P. squamosissimus had the highest parasite rate, with 98% total prevalence, intensity of infection varying between 1 and 255 and parasite mean abundance totaling 40.5 ± 9.9. H. malabaricus had the next parasite rate, with 66.6% total prevalence, parasite intensity between 2 and 184 and mean abundance totaling 22.4 ± 20.9. Cichla sp. had a total prevalence of 52.1%, intensity between 1 and 21, and mean abundance 4.3 ± 2.9. Finally, G. surinamensis had a total prevalence of 46.1%, intensity between 1 and 53 and mean abundance 7.1 ± 8.8. A survey of diplostomid infection in Brazil and the role of piscivore fish as an important host have also been discussed.

This study aimed at identifying and quantifying the parasites of wild and cultured dusky grouper Epinephelus marginatus. During a year and thereby all four seasons, 20 wild and 20 cultured groupers were examined for the presence of parasites, except in the last season, in which 19 wild and 20 cultured fish were examined, totalling 159 groupers analysed from Ubatuba, southeastern Brazil. Prevalence, mean intensity of infection, mean abundance and mean relative dominance were calculated. Five species of parasites were identified in fish from both origins: Pseudorhabdosynochus beverleyburtonae (Monogenea), Neobenedenia melleni (Monogenea), Pseudempleurosoma sp. (Monogenea), Helicometrina nimia (Digenea) and larvae of Contracaecum sp. (Nematoda). The prevalence of ectoparasites, in most cases, was higher than endoparasites. The most abundant parasite was the monogenea Pseudorhabdosynochus beverleyburtonae in both wild and cultured fish, along all seasons. Neobenedenia melleni was observed in wild and cultured fish in all seasons, with a gradual increase in the number of parasites from the coldest to the hottest seasons, with the highest prevalence and mean intensity in the summer. Helicometrina nimia was found in all seasons in both wild and cultured fish, except for summer, where its presence was detected only in wild fish. Pseudempleurosoma sp. and larvae of Contracaecum sp. showed low prevalence occurring in wild and cultured fish in the autumn and spring, respectively. This study revealed high intensities of potentially pathogenic parasites that could favour disease outbreaks in culture conditions.