Journal of Aquaculture Development

fa بررسی باکتریایی و آسیب‌شناسی زخم‌های جلدی در ماهی کاراس (Carassius gibelio) تالاب انزلی Bacteriological and pathological investigation of skin wounds in Prussian carp (Carassius gibelio) تخصصي Special پژوهشي Research <div style="text-align: justify;">     در سه دهه گذشته ماهی غیربومی و کم ارزش کاراس (Carassius gibelio)  بخش قابل توجهی از صید تالاب انزلی را به خود اختصاص داده است. در سالهای اخیر در اواخر زمستان و با آغاز بهار زخمهای عمیق جلدی در ناحیه پهلوها یا قاعده یکی از بالهها در تعدادی از ماهیان کاراس صید شده از تالاب انزلی مشاهده شده است. به‌منظور بررسی دلایل بروز این زخمها از اسفند 1402 تا خرداد 1403 تعداد 30 قطعه ماهی کاراس که علائم کلینیکی را نشان میدادند با وزن متوسط 50±250 گرم مورد بررسی قرارگرفتتند. از محل زخمها و اندامهای داخلی نظیر کبد، طحال و کلیه بر روی محیطهای پایه و اختصاصی کشت باکتریایی انجام شد. جهت مطالعه آسیب شناسی بافتی و بررسی میزان آسیب وارده به بافتهای پوست و عضلات نیز از محل زخمها نمونهبرداری و مقاطع بافتشناسی تهیه گردید. براساس نتایج حاصل از کشت اولیه و انجام آزمایش‌های بیوشیمیایی در نهایت دو باکتریAeromonas hydrophila   وPseudomonas aeruginosa  شناسایی شدند. در بررسی آسیبشناسی بافت پوست و عضله، تخریب وسیع در ناحیه اپیدرم و درم مشاهده شد. همچنین نفوذ شدید لکوسیتها به ناحیه درم نشاندهنده وجود التهاب در این ناحیه بود. ساختار طبیعی درم دچار آسیب شده و ساختارهایی کیست مانند در آن مشاهده گردید. نکروز در رشتههای عضلانی و تجزیه سلولهای ماهیچهای نیز از دیگر آسیبهای مشاهده شده در این ماهیان بود. بیماری ناشی از این باکتریهای فرصتطلب اغلب به‌دنبال شرایط تنشزای محیطی رخ میدهد. این باکتریها، در صورت مصرف ماهیان خام یا نیمپز میتواند به انسان نیز منتقل شود. پیشگیری از ورود انواع آلایندهها و فاضلابها به رودخانههای منتهی به تالاب انزلی میتواند مانع از بروز چنین بیماریهایی در آبزیان گردد. </div> Introduction: Anzali Wetland, as one of the most important wetlands in the north of the Iran, has many ecological and biodiversity values. Among the fish of Anzali Wetland, the Prussian carp Carassius gibelio (Bloch, 1782) is an alien species for which there is no precise information about when and how it entered to Anzali Wetland.Unfortunately in the past three decades, this non-native and low-value fish has accounted for a significant portion of the catch from Anzali Wetland. In recent years 20 to 30 percent of Prussian carp caught from Anzali Wetland in late winter and early spring, has been showing symptoms such as scale loss, skin ulcers on the trunk and base of the fins, which in some cases were accompanied by bleeding, and exophthalmia. Based on clinical signs, the disease was suspected to bacterial infection. Material and Methods: In order to investigate the causes of these ulcers, 30 Prussian carp showing clinical signs with an average weight of 250±50 gr were caught and subjected to bacteriological and histopathological examinations from february 2024 to May 2024. After sampling from the wound site and major internal organs such as the liver, spleen, and kidneys, culture was performed on basic and specific media such as BA and TSA. Then, pure cultures were prepared from the various bacteria grown in these media. Finnaly the bacteria were identified by biochemical tests (Macfaddin, 2000; Garrity et al., 2001). For histopathological examination a tissues sample with 5 mm diameter was removed from the wound site and placed in Bowen’s solution. After dehydration and clarification, the tissues were embedded in paraffin. Sections with a thickness of 5-7 µm were prepared using a microtome. The tissue sections stained with hematoxylin-eosin and a coverslip was attached to each tissue slide. The sections were imaged and studied by light microscopy (Roberts, 2001). Results and Discussion: Based on the results of the initial cultivation and biochemical tests, two bacteria, Aeromonas hydrophila and Pseudomonas aeruginosa, were identified. Both are gram-negative, motile, and opportunistic bacteria. Aeromonas hydrophila can cause bacterial hemorrhagic septicemia in fish. On the other hand Pseudomonas aeruginosa is another waterborne pathogen that has become a major public health concern. In the pathological examination of skin and muscle tissues, extensive destruction was observed in the epidermis and dermis. Also, severe infiltration of leukocytes into the dermis indicates the presence of inflammation in this area. The normal structure of the dermis was damaged and cyst-like structures were observed in it. myofiber necrosis, decomposition of muscle cells and myolysis of muscular tissue were also among the other damages observed in these fish. Diseases caused by these opportunistic bacteria occur under environmental stressors conditions. These bacteria, especially Aeromonas hydrophila, are zoonotic and can be transmitted to humans through the consumption of raw or undercooked fish. Conclusion: Severe skin lesions in prussian carp can be caused by physical damage from natural predators of these fish in Anzali wetland or escape from gill nets, which can lead to secondary bacterial infections. Bacterial cepticemia caused by Aeromonas hydrophila is one of the most common infectious diseases of Carassius genus. Since these fish are finally included in community food basket, the importance of paying attention to the health of Anzali Wetland is doubled. It is very important and necessary to observe sanitary standards in the disposal of urban, hospital, agricultural, and industrial wastewater, and especially to accelerate the construction of efficient treatment plants for coastal cities in order to prevent of the entry of various pollutants and sewages into the rivers leading to the Anzali Wetland can prevent the occurrence of such diseases in aquatic animals. Aeromonas hydrophila , Pseudomonas aeruginosa, آسیب‌شناسی, سپتی‌سمی باکتریایی, خونریزی دهنده Aeromonas hydrophila, Pseudomonas aeruginosa, Pathology, Bacterial hemorrhagic septicemia 121 134 http://aqudev.lahijan.iau.ir/browse.php?a_code=A-10-623-2&slc_lang=fa&sid=1 Javad Daghigh Roohi1 جواد دقیق روحی1 javad_daghigh@yahoo.com 100319475328460012313 100319475328460012313 Yes Alireza Mirzajani1 علیرضا میرزاجانی1 armirzajani@gmail.com 100319475328460012314 100319475328460012314 No Monireh Faeed1 منیره فئید1 faeedm@gmail.com 100319475328460012315 100319475328460012315 No Mohaddeseh Ahmadnezhad1 محدثه احمدنژاد1 mohadesehahmadnezhad@gmail.com 100319475328460012316 100319475328460012316 No