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This study aimed to isolate native lactic acid bacteria of yellow tail lambari (Astyanax bimaculatus) and evaluate their effect on host microbiota and gut morphology, as well as survival after experimental challenge. The isolated bacterial strains were evaluated for their inhibition against pathogenic bacterial strains in vitro, and the strain with highest inhibitory ability was molecularly identified as Lactobacillus spp. For in vivo testing, eighty fish were distributed in ten tanks equipped with a recirculation system. The experimental units were divided into two treatments: fish fed with Lactobacillus spp. supplement and fish fed an unsupplemented diet (control). After 30 days, guts from three fish from each experimental unit were pooled for microbiological and histological analysis. The other five fish were inoculated with 2.1x10 4 CFU.mL -1 of Aeromonas hydrophila to evaluate survival after 24h. Lambaris fed with the probiotic diet had a lower count of Vibrios spp., Pseudomonas spp. and Staphylococcus spp., and a higher count of lactic acid bacteria compared to control treatment, as well as, increased length, width and perimeter of intestinal villi, as well as higher survival rate (16.2%) after experimental challenge compared to the unsupplemented group. The results show that the Lactobacillus spp. used has effect probiotic for yellow tail lambari.Keywords: Lactobacillus, yellow tail lambari, gut morphology, microbiota, experimental challenge RESUMO Este estudo objetivou isolar bactéria ácido-láctica nativa do lambari-do-rabo-amarelo (Astyanax bimaculatus) e seu efeito na microbiota e morfologia do trato digestório do hospedeiro, assim como a sobrevivência após um desafio experimental. As bactérias isoladas foram avaliadas quanto a suas inibições in vitro

The genus Dermocystidium is very comprehensive in the host and site of infection, however this is the first report of the occurrence of Dermocystidium sp. in the gills of Nile tilapia. This study was carried out in a fish farming located in the state of Santa Catarina, Brazil. No mortalities were reported in the facility studied and the animals were clinically healthy. During the histopathological analysis of the gills, 8.33% of the fish presented spores of Dermocystidium sp. in the gill tissue. The spores reported herein had a mean length and width of 6.206 x 5.233 μm and a refractile body diameter of 1.965 μm and were studied by histopathology and Transmission electron Microscopy. This study highlights the importance of a new branchial pathogen in farmed tilapia, as well as to its pathogenic potential, considering the outbreaks of mortalities associated with other fish species.

ABSTRACT. This study aimed to characterize the metazoan parasitic fauna associated with freshwater farmed ornamental fish in Southern Brazil. Between July 2014 and January 2015, a total of 423 fish belonging to nine species were examined: Pterophylum scalare, Betta splendens, two varieties of Carassius auratus, Danio rerio, Xiphophorus helleri, two varieties of Xiphophorus maculatus, Poecilia sphenops, Tanichthys albonubes and Puntius sachsii. In each fish collection, the water quality parameters were measured. Specimens were obtained from three ornamental fish farms located in three micro-regions in the State of Santa Catarina (Araquari, Biguaçu and Camboriú). Parasitological indexes were obtained after qualitative and quantitative parasitological analysis. Monogenean parasites, nematodes, and cestodes were found in all facilities. Nevertheless, nematodes and monogeneans presented 100% of prevalence in P. scalare from Araquari. From the analyzed species, P. scalare showed the highest parasite richness.

This study aimed to evaluate the hematological profile and relative condition factor of naturally parasitized Nile tilapia from 12 fish farms in southern Brazil. A total of 240 fish were collected from four regions of the state of Santa Catarina. They were anesthetized, and the blood was collected by puncturing the caudal vein. Subsequently, the fish were necropsied for parasitological analysis. The results were compared with the Kruskal-Wallis test, and the correlations were verified with the Spearman test (P < 0.05). The parasitological analysis revealed high infestations by Ichthyophthirius multifiliis on the fish gills of the south and west regions. The presence of Trichodina magna and Trichodina compacta was observed in low intensity on the body surface of fish from all facilities. Trichodina spp. was found in high intensity parasitizing the fish gills of northern, Itajaí valley and western regions, nonetheless, in those regions, the presence of Monogenea, Cichlidogyrus sclerosus, and Cichlidogyrus halli, on fish gills was observed. The hematological profile presented altered parameters, featuring monocytosis and thrombocytopenia, possibly associated with high parasitic intensities. The observed correlations suggest that neutrophils and monocytes are directly involved in an organic defense against parasites. Monocytes are mainly targeted in the defense against I. multifiliis.

ABSTRACT. The ornamental fish aquaculture represents a consolidated market worldwide. In Brazil, the major volume of commercialized freshwater ornamental fish is originated from fish farms managed by small and midsized farmers. The aim of this study was to characterize the metazoan parasitic fauna associated with the main freshwater ornamental fish farmed in Southern Brazil. Between July 2014 and January 2015, 423 fishes belonging to nine freshwater species were examined: angelfish Pterophylum scalare, siamese fighting fish Betta splendens, telescope and comet goldfish Carassius auratus, zebrafish Danio rerio, blood red swordtail Xiphophorus helleri, caramel and wagtail platy fish Xiphophorus maculatus, black molly Poecilia sphenops, white cloud mountain minnow Tanichthys albonubes and goldfinned barb Puntius sachsii. Water quality was measured in fishponds from each facility. Specimens were obtained from three ornamental fish farms located in three micro-regions in the State of Santa Catarina (Biguaçu, Camboriú e Joinville). Parasitological indexes were obtained after parasitological analysis of mucus, gills, and eyes. Trichodinids, Piscinoodinium pillulare, and Ichthyophthirius multifiliis were found in all fish farms analyzed. However, P. pillulare showed the greatest prevalence and mean intensity, compared to the other protozoa analyzed. 75% prevalence and mean intensity 57.5 were observed in the gills of P. scalare from fish farm Araquari. This study showed that fish farm Biguaçu, was the facility presenting the greatest parasite diversity. P. scalare and C. auratus were the most parasitized fish species presenting the higher richness when compared to another species. These ornamental species are widely traded and require greater care in cultivation because it is essential to produce healthy fish with attractive features accepted by the market.

The monogenean parasites are one of the most important pathogens causing economic losses in fish farming worldwide. This study aimed to evaluate parasitological indexes of Gussevia spiralocirra in juvenile Pterophyllum scalare, in the warm and cool season. A total of 34 fish were examined for parasitological analysis and the water quality was measured during the experimental period. The gills were fixed in 5% formalin solution for quantification and the parasites were mounted in Hoyer´s medium for identification. The parasitic species was identified as Gussevia spiralocirra, and presented a prevalence of 100%. The mean abundance and mean intensity of infestation were significantly higher in fish during the warm season (784.0 ± 393.9) than that observed in the cool season (418.0 ± 111.2). Temperature did influence the biology of G. spiralocirra possibly by increasing the oviposition rate. This study presents important data that can be used for implementation of best management practices in ornamental P. scalare farming, especially in the hottest seasons of the year.

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