The aim of this article was to evaluate the influence and effects of chosen bioaccumulative substances i.e. heavy metals, pesticides, and polychlorinated biphenyls (PCBs) on fish, as well as provide information on time trends and potential threat to human health. Chemical substances which pollute water may affect living organisms in two ways. First of all, large amounts of chemical substances may cause sudden death of a significant part of the population of farmed fish, without symptoms (i.e. during breakdown of factories or industrial sewage leaks). However, more frequently, chemical substances accumulate in tissues of living organisms affecting them chronically. Heavy metals, pesticides, and polychlorinated biphenyls are persistent substances with a long-lasting biodegradation process. In a water environment they usually accumulate in sediments, which makes them resistant to biodegradation processes induced by, e.g., the UV light. These substances enter the fish through direct consumption of contaminated water or by contact with skin and gills. Symptoms of intoxication with heavy metals, pesticides, and PCBs may vary and depend on the concentration and bioavailability of these substances, physicochemical parameters of water, and the fish itself.

Introduction: In the present study, some of the commercial fish farms located in the Black Sea region of Turkey, were screened for bacteria between 2012 and 2014.

Objective: This cross-sectional study was conducted from April to July 2014 in Khartoum state, the Sudan, to investigate aerobic bacteria and fungi of skin lesions of fish in 3 different areas in Khartoum. Material and methods: A total of 50 samples were collected from the skin lesions of different types of fish including Synodontis species (n=17), Tilapia niloticus (n=15), Labeo niloticus (n=10), Hydrocynus species (n=4), and Clarias species (n=4). Liquid, semi-solid, and solid culture media like nutrient broth, blood agar, MacConkey agar, sabouraud dextrose agar (SDA), and Simmons citrate medium were used for the isolation and identification of bacteria and fungi. Besides, Gram staining and biochemical characterization were also conducted.Results: Culturing of the collected samples revealed growth of bacteria from all (100%), and growth of fungi could be found from 32% samples. A number of 188 bacteria were isolated, mainly Staphylococcus species, Bacillus species, Aeromonas species, Pseudomonas species, and Vibrio species. Besides, 16 fungi could be identified containing Aspergillus niger, A. flavus, A. fumigatus, and Phycomycete.Conclusion: Fishes with skin lesions are harboring many pathogenic bacteria and fungi and may act as a source of zoonotic infections and can transmit several pathogens to workers in fish industry and consumers. Therefore, thorough and strict routine inspection of fish is recommended to ensure safety and that there are no serious risks to consumers. [J Adv Vet Anim Res 2016; 3(4.000): 375-385]