In the first part of the study, 70 aquarium fish of different species, originating from stocks from the CzechRepublic, were pathomorphologically examined for the presence of granulomatous lesions. Granulomas were diagnosed in 44 (62.9%) fish. From these, acid fast rods (AFR) were found in 29 (65.9%) by staining according to Ziehl-Neelsen (Z-N). In the remaining 26 (37.1%) fish without granulomatous lesions, the presence of AFR was microscopically proven in 3 (11.5%) fish. In the second part of the study, direct microscopic examinations accord­ing to Z-N and culture examinations for the presence of mycobacteria were carried out in 17 randomly selected fish of the Apistogramma cacatuoides, Trichogaster leeri, Trichogaster trichopterus, Pterophyllum scalare, Paracheirodon axelrodi species with the pathomorphological discovery of granulomas. Mycobacteria were culturally found in 12 (70.6%) fish. Mycobacterium marinum, pathogenic for fish, was isolated from 6 fish, of which in one M. triviale was found at the same time and in two M. avium mixed serotypes 6, 8 and 9 (genotype IS901–, IS1245+). M. gordonae was isolated from a further 6 fish, of which in two M. avium mixed serotypes 6, 8 and 9 (genotype IS901–, IS1245+) was also isolated at the same time. A mixed infection of more species of mycobacteria was therefore found in five fish. In these it may be assumed that the mycobacteria of the M. triviale and M. avium mixed serotypes 6, 8 and 9 (genotype IS901–, IS1245+), non-pathogenic for fish, came from the water environment and “merely contaminated” the tissues of the fish.

No abstract

Two species of common edible fish, common carp (Cyprinus carpio) and silver carp (Hypophthalmichthys molitrix), were exposed to a Microcystis spp.-dominated natural cyanobacterial water bloom for two months (concentrations of cyanobacterial toxin microcystin, 182-539 microg/g biomass dry wt). Toxins accumulated up to 1.4 to 29 ng/g fresh weight and 3.3 to 19 ng/g in the muscle of silver carp and common carp, respectively, as determined by enzyme-linked immunosorbent immunoassay. Concentrations an order of magnitude higher were detected in hepatopancreas (up to 226 ng/g in silver carp), with a peak after the initial four weeks. Calculated bioconcentration factors ranged from 0.6 to 1.7 for muscle and from 7.3 to 13.3 for hepatopancreas. Microcystins were completely eliminated within one to two weeks from both muscle and hepatopancreas after the transfer of fish with accumulated toxins to clean water. Mean estimated elimination half-lives ranged from 0.7 d in silver carp muscle to 8.4 d in common carp liver. The present study also showed significant modulations of several biochemical markers in hepatopancreas of fish exposed to cyanobacteria. Levels of glutathione and catalytic activities of glutathione S-transferase and glutathione reductase were induced in both species, indicating oxidative stress and enhanced detoxification processes. Calculation of hazard indexes using conservative U.S. Environmental Protection Agency methodology indicated rather low risks of microcystins accumulated in edible fish, but several uncertainties should be explored.

The aim of this study was to investigate the effect of intraperitoneally applied Microcystin LR to the health condition of silver carp (Hypophthalmichthys molitrix Val.) stockfish by means of assessment of haematological. biochemical and morphological indices.Two-year-old stockfish of silver carp was used for experiments. In the first trial. pure Microcystin LR was applied to the tish intrar.eritoneally in dose of250 ~g' kg· l body weight (bw). A pure Microcystin LR dose of 400 ~g . kg' bw was used in the second experiment. After 48 hours. fish were sampled for blood by cardiopunction to determine the erythrocyte count (RBC

Navratil S., M. Palikova. V. Vajcova: The Effect