This article presents the results of a study of the hydrochemical regime of water bodies in the Karaganda region, the Republic of Kazakhstan, and assesses the safety of fish. It was established that the hydrochemical regime of the water bodies was within the permissible concentration, however, a decreased permanganate oxidation was noted, which indicates a satisfactory state of water quality. Widespread infection of fish with postdiplostomatosis was revealed in assessing fish safety; in rare cases, diplostomosis and ligulosis were detected. The incidence of fish with bacteriosis was not observed, with the exception of isolated cases of aeromonosis. Exceeding the maximum permissible concentrations for residual amounts of toxic elements and radionuclides has not been established. We found that the most common fish disease in the water bodies of the Karaganda region was postdiplostomatosis, which was diagnosed in the roach in all the water bodies of three regions, and the most infection was observed in the fish of the DSU-58 reservoir in the Nurinsky district, where the infestation rate was 42.8%, intensity 3-5. Most likely this is due to the presence of fish-eating birds (herons and tree frogs) and a large number of gastropods in these reservoirs. We detected isolated cases of fish infection with diplostomiasis in roach from Lake Toxumac, where IR was 12.5%. This is due to the presence of gulls and pond mollusks on this lake, which are the main links in the helminth’s life cycle. We have also identified isolated cases of ligulosis in roach and crucian carp from the “DSU-58” dam, where, respectively, IR was 27 and 14.2%. The presence of this disease is associated with the presence of fish-eating birds and crustaceans in this pond.