Fusarium infections have been reported in aquatic animals, but are still poorly investigated in wild salmonids. The aim of the study was to determine the impact of the fungi and their toxins on the health status of brown trout (Salmo trutta morpha trutta) migrating from the Baltic Sea to the freshwater. Individuals from the wild brown trout population exhibiting ulcerative skin lesions were collected from the Słupia River in Poland and subjected to microbiological, histopathological, and hematological examinations, as well as toxicological analysis for a presence of mycotoxins. The results of microflora isolation from the brown trout skin samples revealed the presence of conditionally pathogenic bacteria and fungi classified by molecular techniques as Fusarium spp. Toxicological analysis allowed for detection of zearalenone (ZEN) in the liver, kidney, and gastrointestinal tract of the fish. In several cases, there was α-zearalenone (α-ZEL) identified at trace levels in the liver, as well as sterigmatocystin and enniatin B at low levels in the kidney and the liver. Histopathological examination revealed the presence of fungal hyphae disrupting the epidermis and penetrating into the necrotic dermis and hypodermis. The decreased values of the blood parameters, i.e., hemoglobin concentration (HGB), packed cell volume (PCV), mean corpuscular volume (MCV), mean corpuscular hemoglobin (MCH), and white blood cell count (WBC), were indicative of osmoregulation failure being a consequence of the skin damage. The results of the study provide new information regarding Fusarium sp. infection in brown trout and serve as the basis for further research on the potential impact of the fungi and their mycotoxins on the Baltic salmonid population, including their role in ulcerative dermal necrosis.

中文翻译：

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可产生霉菌毒素的镰刀菌。在褐鳟（Salmo trutta morpha trutta）的溃疡性皮肤坏死（UDN）中发挥作用？

已有水生动物感染镰刀菌的报道，但对野生鲑鱼的研究仍然很少。该研究的目的是确定真菌及其毒素对从波罗的海迁移到淡水的褐鳟（Salmo trutta morpha trutta）健康状况的影响。从波兰的斯乌皮亚河收集表现出溃疡性皮肤病变的野生褐鳟鱼种群的个体，并对其进行微生物学、组织病理学和血液学检查，以及是否存在霉菌毒素的毒理学分析。从褐鳟鱼皮样品中分离出的微生物群落结果表明存在条件性致病细菌和真菌，分子技术将其分类为镰刀菌属 毒理学分析允许在鱼的肝脏、肾脏和胃肠道中检测到玉米赤霉烯酮 (ZEN)。在几个案例中，肝脏中发现了痕量水平的 α-玉米赤霉烯酮 (α-ZEL)，肾脏和肝脏中也发现了低水平的 sterigmatocystin 和 enniatin B。组织病理学检查显示存在破坏表皮并渗入坏死真皮和皮下组织的真菌菌丝。血液参数值的降低，即血红蛋白浓度 (HGB)、压实细胞体积 (PCV)、平均红细胞体积 (MCV)、平均红细胞血红蛋白 (MCH) 和白细胞计数 (WBC)，表明渗透调节失败是皮肤损伤的结果。研究结果提供了有关以下方面的新信息镰刀菌。褐鳟感染，并作为进一步研究真菌及其真菌毒素对波罗的海鲑鱼种群的潜在影响的基础，包括它们在溃疡性皮肤坏死中的作用。