Effect of nutraceuticals on acanthocephalan Neoechinorhynchus buttnerae and its toxicity to the host tambaqui Colossoma macropomum.

The production of tambaqui Colossoma macropomum has been undergoing financial losses due to parasitic infection by the acanthocephalan Neoechinorhynchus buttnerae, raising an alert for aquaculture in South America. The lack of adequate treatment and use of unlicensed chemicals encourages research for alternative solutions with minimal side effects. The objectives of this study were to evaluate the in vitro antiparasitic potential of commercial nutraceutical products (Natumix® and BioFish®) against N. buttnerae and to assess the respective in vivo toxic effects on the host tambaqui. For in vitro assays, parasitized fish were necropsied for acanthocephalans sampling. The parasites were exposed to three concentrations (0.078, 0.313 and 1.25 mg/ml) of each product, as well as controls (one without product and another with a solubilizer). For the in vivo acute toxicity test, juvenile fish (<0.1 g) were exposed to five increasing concentrations of each product. Mortality of tambaqui was recorded at 24, 48, 72 and 96 h. The estimated lethal concentration (LC) for 10, 50, 90 and 99% of fish was determined to classify the toxicity of the products on the target species. After in vitro efficacy tests, the highest concentrations (1.25 mg/ml) caused 100% mortality of the parasites in both products, but only Natumix® caused 100% mortality using the intermediate concentration (0.313 mg/ml) after 24 h. According to the acute toxicity result, the LC50 classified the nutraceutical products as slightly toxic for tambaqui. The tested products had a parasiticidal effect on N. buttnerae, and the toxicity test showed that both products have therapeutic potential when added to the diet.

Tadpoles fed supplemented diet with probiotic bacterium isolated from the intestinal tract of bullfrog Lithobates catesbeianus: Haematology, cell activity and electron microscopy.

The aim of this study is to select and isolate autochthonous bacteria with probiotic potential for use in a supplemented diet for bullfrog tadpoles, Lithobates catesbeianus. A total of 20 strains of lactic acid bacteria were isolated. Nine out of these were used in the following in vitro assays: antagonism against pathogenic bacteria (ANT), antimicrobial activity from extracellular compounds (MIC), tolerance to bile salts (TBS), pH reduction, protease production, sensitivity to antimicrobial tetracycline, cell viability, growth rate and doubling time. Using these data was defined an ideotype (ideal strain) based on the best results. Distances were estimated with the Mahalanobis (D2) test, and the best candidates, presenting the shortest ideotype distances, were considered to be used. The best strain was found to be Lactobacillus plantarum because it presented 10.00 ± 0.50 mm of ANT against Aeromonas hydrophila, 3.99 ± 0.01 of MIC independent of pathogenic bacteria, 85.07 ± 0.01 of TBS, 4.20 ± 0.02 of final pH, 17.67 ± 1.15 of protease production, 13.50 ± 2.00 sensitivity to antimicrobial tetracycline, 9.36 ± 0.04 of cell viability, 0.20 ± 0.00 of growth rate and 3.46 ± 0.00 doubling time. Therefore this probiotic candidate was then supplemented (2.045 ± 1.07 × 107 colony forming unities. g-1) into the diets of bullfrog tadpoles for a period of 42 days. At the end of the trial, samples of blood and intestines were collected to verify the haematological alterations and the intestinal morphology using transmission and scanning electron microscopy. Tadpoles fed the supplemented diet showed successful lactic acid bacterium colonisation, an increased number of circulating thrombocytes, monocytes, eosinophil and LG-PAS+ and also an increase in the length and density of intestinal microvilli. This study shows the feasibility of using probiotics isolated from farmed bullfrogs as a supplement in the diets of tadpoles, providing a promising alternative for modulating the health of these animals.

Haematological and histopathological analysis in South American fish Piaractus mesopotamicus parasitized by monogenean (Dactylogyridae).

Monogeneans are the parasites mostly found on the body surface and gills of fish and can cause large losses in farmed fish. Some studies demonstrate elevated parasitic levels causing hematological alterations. But few of them relate the effects of parasitism on the hematology and histopathology of native freshwater farmed fish. This study evaluated the host-parasite relationship in pacu (Piaractus mesopotamicus) parasitized by the monogenean Anacanthorus penilabiatus. Hematological and parasitological assessments were obtained in 60 fish captured in a fish farm located in Dourados, State of Mato Grosso do Sul, Central Brazil. Fish were analyzed in different categories of parasite number: class I (n=13; 0-200 parasites), class II (n=17; 201-1200 parasites); class III (n=7; 1201-2200 parasites); and class IV (n=23; more than 2200 parasites per host). The highest levels of parasitism caused significant decrease (p<0.05) in the hematocrit, red blood cells (RBC), mean hemoglobin concentration (MCHC) and basophils number. Thrombocytes, mean corpuscular volume (MCV), mean corpuscular hemoglobin concentration (MCHC), monocytes, eosinophils, neutrophils and LG-PAS did not present significant difference among the parasitic levels. In contrast, increased number of total leukocytes and lymphocytes were found in highly-parasitized fish. A positive linear correlation (p<0.01) was found between the amount of parasites and fish weight. Histopathology revealed severe hyperplasia, sub-epithelial edema, fusion of the secondary lamellae, focal and multifocal necrosis in highly parasitized fish.

First record of Chilodonella hexasticha (Ciliophora: Chilodonellidae) in Brazilian cultured fish: a morphological and pathological assessment.

Chilodonelids are small ciliated protozoans found worldwide and can be dangerous in culture conditions. This study presents morphometric data on the ciliate Chilodonella that is found in cultured Nile tilapia (Oreochromis niloticus), native bait fish tuvira (Gymnotus aff. inaequilabiatus) and native pacu (Piaractus mesopotamicus) and includes a histopathological assessment of the changes that occur in the pacu. For parasitic diagnosis, skin and gill samples were scraped onto slides, dried at room temperature, stained with Giemsa or impregnated with silver nitrate, and the measurements were obtained from photomicrographs. In the diseased pacu, the first gill arch was collected and fixed in a 10% buffered formalin solution for histopathological analysis. Parasite specimens from the different collection sites were identified morphologically as C. hexasticha Kiernik (1909). Diseased fish exhibited depigmentation, skin ulceration, scale loss, excessive mucus production and gill lesions. Histopathological analysis of pacu gills displayed epithelial proliferation with mononuclear inflammatory infiltrate, hemorrhages, and scattering necrosis. In Brazilian-farmed fish this is the first record of C. hexasticha, which has great pathogenic potential in cultured freshwater species. In addition, two new hosts are presented.

Seasonal influence on the hematological parameters in cultured Nile tilapia from southern Brazil.

This study evaluated seasonality in hematological parameters of Nile tilapia cultured in the state of Santa Catarina, southern Brazil. A total of 240 fish were examined during four seasons between April 2007 and March 2008 in three different fish farms. After being anesthetised in a benzocaine solution, blood samples were withdrawn into syringes containing a drop of 10% EDTA for hematological analysis. The results were compared between fish farms and seasons, which are well delimited in southern Brazil. In a traditional fish farm in Joinville in the summer, there was an increase in the percentage of hematocrit and in the red blood cell count. The highest values of total leukocytes were found in fish from fee-fishing in Blumenau in the autumn while the lowest values occurred in those from swine consorted system in Ituporanga in the summer. Thrombocytosis was observed in the autumn, and lymphocytosis was found in both the autumn and winter in tilapia from all fish farms investigated. Neutrophilia was only observed in winter and autumn in fish from Blumenau and Ituporanga. This work demonstrated the influence of seasonality and the handling characteristics of each fish farm on certain hematological parameters in Nile tilapia.

Parasite diversity in Oxydoras niger (Osteichthyes: Doradidae) from the basin of Solimões River, Amazonas state, Brazil, and the relationship between monogenoidean and condition factor.

This study describes the parasitic fauna of Oxydoras niger from the Coari Lake, tributary of the medium Solimões River, State of Amazonas, Brazil, and the relationship between the number of Monogenoidea and the condition factor. From a total of 27 examined fish, 70.3% were parasitised by at least one parasite species as follows: Ichthyophthirius multifiliis (Protozoa), Chilodonella sp. (Protozoa), Cosmetocleithrum gussevi, C. confusus, C. parvum and Cosmetocleithrum sp. (Monogenoidea), Paracavisona impudica (Acanthocephala), Cucullanus grandistomis (Nematoda), Proteocephalus kuyukuyu (Cestoda) and Dadaytrema sp. (Digenea). Monogenoidea helminthes were the most prevalent parasite when compared to protozoan and intestinal helminthes. This study showed that O. niger has a great parasite diversity composed mainly of monogenoideans followed by acanthocephalan and digenean. This is the first record of Dadaytrema in O. niger from the Brazilian Amazon. There was a positive correlation between the number of monogenoideans and the condition factor (Kn) of fish, and with this mean intensity of infection, fish welfare was not affected.

Seasonal variation on the ectoparasitic communities of Nile tilapia cultured in three regions in southern Brazil.

A total of 240 Nile tilapia were examined between April 2007 and March 2008, gathered from three different fish farms, 20 fish in each fish farm, in the four seasons of the year. Fish ponds were located in Joinville, Blumenau and Ituporanga, Santa Catarina state, Brazil and each pond had a different culture system. Prevalence, mean intensity, mean abundance and mean relative dominance were compared among fish ponds and seasons. During this period, the water quality was kept in normal values. Piscinoodinium pillulare (Dinoflagellida) was the most dominant parasite followed by Trichodina magna e T. compacta (Ciliophora), Cichlydogyrus sclerosus, C halli, C. thurstonae, Scutogyrus longicornis (Monogenoidea), copepodids Lernaeidae gen. sp. The highest prevalence, mean intensity and mean abundance of ectoparasites were found on the body surface in fish from Joinville followed by Blumenau and Ituporanga. In the gills, the highest mean intensity and mean abundance were found in fish from Blumenau and Ituporanga in the winter. Piscinoodinium pillulare showed prevalence 100% during autumn in Blumenau and Ituporanga. In winter P. pillulare occurred in all study facilities. Fish from Joinville showed 100% prevalence of Monogenoidea during all seasons, as well as the highest mean intensity and abundance. The results showed that the majority of examined fish had higher infestations by protozoan during autumn and winter and higher infestations by metazoan have occurred in spring and summer.

Haematological changes in Nile tilapia experimentally infected with Enterococcus sp.

This study evaluated the haematological changes in Nile tilapia experimentally infected with 1 x 10(3) and 1 x 10(6) colony-forming units (CFU)/mL of Enterococcus sp. in the swim bladder. The experiment consisted of four treatments in triplicates: non-injected fish (NI); fish injected with 1 mL of sterile saline solution 0.65% (SAL); fish injected with 1 x 10(3) and 1 x 10(6) CFU/mL of Enterococcus diluted in 1 mL sterile saline. Twenty-four hours after injection, the fish were anesthetized and the blood collected. The haematological tests included red blood cell (RBC) and white blood cell (WBC) counts, hematocrit, number of total thrombocytes, and differential counting of WBC. Fish injected with 1 x 10(6) CFU/mL of Enterococcus showed a higher number of thrombocytes than the other treatments. White blood cell and lymphocyte numbers increased significantly in fish injected with 1 x 10(6) CFU/mL of Enterococcus when compared to non-injected control. There was significant increase in the number of neutrophils in saline injected fish and reduced number of monocytes after injections with 1 x 10(6) CFU/mL of Enterococcus. Hematocrit increased in fish injected with 1 x 10(3) and 1 x 10(6) CFU/mL of Enterococcus.

Haematological changes in Nile tilapia experimentally infected with Enterococcus sp[period] / Alterações hematológicas em tilápia do Nilo infectada experimentalmente com Enterococcus sp[ponto final]

This study evaluated the haematological changes in Nile tilapia experimentally infected with 1 x 10³ and 1 x 10(6) colony-forming units (CFU)/mL of Enterococcus sp. in the swim bladder. The experiment consisted of four treatments in triplicates: non-injected fish (NI); fish injected with 1 mL of sterile saline solution 0.65 percent (SAL); fish injected with 1 x 10³ and 1 x 10(6) CFU/mL of Enterococcus diluted in 1 mL sterile saline. Twenty-four hours after injection, the fish were anesthetized and the blood collected. The haematological tests included red blood cell (RBC) and white blood cell (WBC) counts, hematocrit, number of total thrombocytes, and differential counting of WBC. Fish injected with 1 x 10(6) CFU/mL of Enterococcus showed a higher number of thrombocytes than the other treatments. White blood cell and lymphocyte numbers increased significantly in fish injected with 1 x 10(6) CFU/mL of Enterococcus when compared to non-injected control. There was significant increase in the number of neutrophils in saline injected fish and reduced number of monocytes after injections with 1 x 10(6) CFU/mL of Enterococcus. Hematocrit increased in fish injected with 1 x 10³ and 1 x 10(6) CFU/mL of Enterococcus.

Este estudo avaliou alterações hematológicas em tilápia do Nilo infectada experimentalmente com 1 x 10³ e 1 x 10(6) unidades formadoras de colônia (CFU)/mL de Enterococcus sp. na bexiga natatória. O experimento consistiu de quatro tratamentos com três repetições cada: peixes não injetados (NI); peixes injetados com 1 mL de solução salina a 0,65 por cento esterilizada (SAL); peixes injetados com 1 x 10³ e 1 x 10(6) CFU/mL de Enterococcus diluída em 1 mL de solução salina esterilizada. Vinte e quatro horas após as injeções, os peixes foram anestesiados com benzocaína e o sangue coletado. Os testes hematológicos incluíram as contagens totais de eritrócitos (RBC), de leucócitos (WBC) e de trombócitos, o percentual do hematócrito e a contagem diferencial de leucócitos. Peixes injetados com 1 x 10(6) CFU/mL de Enterococcus mostraram maior número de trombócitos no sangue do que os dos outros tratamentos. O número de leucócitos totais e o número de linfócitos foram significativamente mais altos após injeção de 1 x 10(6) CFU/mL de Enterococcus, quando comparados ao controle não injetado. Houve aumento no número de neutrófilos nos injetados com salina e redução no número de monócitos nos injetados com 1 x 10(6) CFU/mL de Enterococcus. O hematócrito aumentou nos animais injetados com 1 x 10³ e 1 x 10(6) CFU/mL de Enterococcus.