This study aimed to identify the cause of sustained mortality in freshwater angelfish (Pterophyllum scalare Schultze, 1823) kept at an ornamental fish production facility in Turkey. Parasitological, bacteriological and histopathological examination were performed on moribund hybrid angelfish individuals. The moribund fish had haemorrhaged eyes, darkened skin, scale loss, ascites and false faeces. A pale liver, splenomegaly and a thinning of the intestinal wall were observed internally. The parasitological examination revealed flagellated protozoan endoparasite Spironucleus sp. in the intestine. A number of histopathological changes were observed including lipid degeneration in the liver, hemosiderin deposits as well as granulomas in the spleen, a large number of mast cells in the lamina propria of the intestine and enteritis. Numerous Spironucleus sp. parasites were seen in the intestinal wall. According to physiological and biochemical tests, the bacterial isolates obtained from the visceral organs of some fish were identified as Citrobacter freundii. After oral metronidazole treatment, with a dose of 50 mg/kg fish daily for 5 days, a decrease in fish mortality and resumed feeding were noted. A chronic spironucleosis, which systematically affects fish by penetrating the intestinal mucosa, was identified as the cause of this sustained mortality in freshwater angelfish.
Aquaculture is arguably the fastest growing industry in global food animal production, but diseases and related mortalities are the main factors that determine the limits of production volume. Fish in aquaculture systems are susceptible to infectious agents as they are kept in a densely populated and often physically restricted environment. Genus Aeromonas include well-known pathogens, and the member Aeromonas veronii has been reported to cause diseases in both humans and animals, either as primary infection or as mixed infection with other pathogens. This study describes a low mortality epizootic caused by Aeromonas veronii biovar veronii in European seabass (Dicentrarchus labrax) farmed in the Aegean Sea. The gills, kidneys and livers of moribund fish were pale. Erythema, haemorrhage and superficial ulcerative lesions were detected on the skin. In addition, petechial haemorrhage was observed on the tongue, maxilla and operculum. The spleen was enlarged and multiple abscesses were detected in both the liver and the spleen. Granulomas were observed in the spleen and the kidney. Some fish had skin depigmentation, ecchymosis in the liver and a bloody exudate in the abdominal cavity. The intestinal walls were lined with a clear yellowish fluid. Twenty-nine motile, Gram-negative bacterial isolates were obtained from the internal organs of diseased fish. According to morphology, biochemical properties and 16S rRNA gene sequencing results, all isolates were identified as Aeromonas veronii bv. veronii. All isolates were resistant to amoxicillin and ampicillin but, only intermediate resistant to sulfamethoxazole/trimethoprim.
Oxidative stress and bacterial infections threaten human and animal health. Different parts of the plants have a great potential to be used as a source of antioxidant and antibacterial agents for human or animal welfare, because of their active metabolites. This study was conducted to assess the antioxidant and antibacterial activities of methanolic extracts from the leaves, flowers, whole fruits, and woods of pomegranate (Punica granatum L.), and the leaves, cones, and woods of Anatolian black pine [Pinus nigra Arn. subsp. pallasiana (Lamb.) Holmboe]. Antioxidant activity was screened by DPPH and CUPRAC assays. Antimicrobial activity was examined by disc diffusion test against fish pathogens, Aeromonas hydrophila, Vibrio anguillarum, Yersinia ruckeri and Lactococcus garvieae. Pomegranate whole fruit extract possessed superior antioxidant activity even higher than ascorbic acid. All parts of pomegranate, except wood, also exhibited significant antibacterial activity against fish pathogens. Black pine cone extract slightly inhibited the growth of fish pathogens while other pine extracts were inactive. This study reveals that the whole fruit of pomegranate is a prominent source of antioxidant and antibacterial metabolites. Cones of Anatolian black pine also seem to be a source of antibacterial compounds against fish pathogens.
The aim of this study was to investigate the effect of whey on the immune system of cultured rainbow trout (Oncorhynchus mykiss). It was targeted to use whey, which is a by-product of the dairy industry, in the aquaculture industry as a promoter of fish immune system and as a source of fish feed protein. Rainbow trout individuals with an average weight of 70.28 ± 1.50 g were placed in 6 tanks with a stock density of 10 kg/m3. While fish meal (52%) was used as a protein source in the control group feeds, in the experimental group feeds whey powder (48%) was used. The fish were fed these pellet feeds that were isocaloric (21 kj / g) and isonitrogenous (41% protein) for 3 weeks. Blood samples were collected once a week and while hematocrit and hemoglobin values were determined using a fully automated hematology analyzer, standard hemocytometry methods were used in erythrocyte and leukocyte counts. In addition, free radical production and complement 3 concentrations were determined quantitatively. According to the one-way ANOVA analysis, the control group and the experimental group were statistically similar (p> 0,05). However, it was found that C3 complement concentration, which was measured equally at the beginning in the control and experimental groups, showed a statistically significant increase (p <0.05) in the experimental group compared to the control group in the second week. This is the first study in Turkey investigating the effect of using whey in fish feeds on the immune system of fish.
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