ABSTRACT: In this study, spontaneous swim bladder mycosis was documented in a farmed fingerling rainbow trout from a raceway culture system. At necropsy, the gross lesions included a thickened swim bladder wall, and the posterior portion of the swim bladder was enlarged due to massive hyperplasia of muscle. A microscopic wet mount examination of the swim bladder contents revealed abundant septate hyphae, and histopathological examination showed periodic acid-Schiff-positive mycelia in the lumen and wall of the swim bladder. Histopathological examination of the thickened posterior swim bladder revealed muscle hyperplasia with expansion by inflammatory cells. The causative agent was identified as Phoma herbarum through morphological analysis and DNA sequencing. The disease was reproduced in rainbow trout fingerlings using intraperitoneal injection of a spore suspension. Necropsy in dead and moribund fish revealed extensive congestion and haemorrhages in the serosa of visceral organs and in liver and abdominal serosanguinous fluid. Histopathological examination showed severe hepatic congestion, sinusoidal dilatation, Kupffer cell reactivity, leukostasis and degenerative changes. Fungi were disseminated to the liver, pyloric caeca, kidney, spleen and heart. Although infections caused by Phoma spp. have been repeatedly reported in fish, species identification has been hampered by extensive taxonomic changes. The results of this study confirmed the pathogenicity of P. herbarum in salmonids by using a reliably identified strain during experimental fish infection and provides new knowledge regarding the course of infection.

中文翻译：

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锦标草引起的养殖虹鳟Onmyhynchus mykiss的游泳膀胱真菌病和致病性的实验验证。

摘要：在这项研究中，自来水道养殖系统的养殖鱼种虹鳟鱼记录了自发性游泳膀胱真菌病。尸检时，大的病变包括增厚的游泳膀胱壁，并且由于肌肉大量增生，游泳膀胱的后部增大。显微镜下对游泳膀胱内容物进行湿式检查发现大量的隔膜菌丝，并且组织病理学检查显示在游泳膀胱内腔和壁中有周期性的酸-席夫氏阳性菌丝体。对后游泳膀胱变厚的组织病理学检查显示，肌肉增生并伴有炎性细胞扩张。病原被鉴定为植物标本通过形态分析和DNA测序。该疾病通过腹膜内注射孢子悬浮液在虹鳟鱼种中繁殖。死鱼和垂死鱼的尸检显示内脏器官浆膜以及肝脏和腹部的血胶质液大量充血和出血。组织病理学检查显示严重的肝充血，正弦扩张，库普弗细胞反应性，白细胞停滞和变性改变。真菌散布到肝脏，幽门盲肠，肾脏，脾脏和心脏。虽然感染是由Phoma spp引起的。在鱼类中已多次被报道，物种识别受到广泛的分类学变化的阻碍。这项研究的结果证实了体育标本的致病性 通过在实验鱼感染过程中使用可靠鉴定出的菌株，可以在鲑鱼中进行捕捞，并提供有关感染过程的新知识。