Myxozoans can induce losses in production of marine and freshwater fish. Recently, a new parasitic myxozoan species, Sinuolinea niloticus, was identified and its importance highlighted. This study aimed to investigate Sinuolinea niloticus and its macroscopic and microscopic alterations in Nile tilapia (Oreochromis niloticus) specimens from fish farms in Botucatu, São Paulo, Brazil, as well as its molecular detection. Thirty tilapias from three different fish farms were collected and submitted to necropsy examination, where organs were sampled for histopathological and molecular analysis. The main necroscopic findings at all three fish farms were hemorrhaging, fin erosion, hepatomegaly, and splenomegaly. Microscopically, the main findings were degeneration of hepatocytes and hepatitis, epithelial and goblet cell hyperplasia in the gills, nephritis, gastritis, and presence of myxozoan-like structures in different organs. S. niloticus, detected by qPCR, showed a 90% prevalence among surveyed fish at farm 1 and 100% at farms 2 and 3. The high prevalence found in this study shows the importance of this myxozoan as a potential pathogenic agent of farmed O. niloticus that negatively affects fish health and, consequently, production.

粘虫类动物会导致海水和淡水鱼生产中的损失。最近，发现了一种新的寄生粘虫动物物种，Sinuolinea niloticus，并强调了其重要性。本研究旨在探讨Sinuolinea罗非鱼及其宏观和微观的变化在尼罗罗非鱼（尼罗罗非鱼）来自巴西圣保罗Botucatu养鱼场的标本，以及分子检测。收集了来自三个不同养鱼场的30条罗非鱼，并进行尸检，从中抽取器官进行组织病理学和分子分析。在所有三个养鱼场中，主要的坏死镜检查结果是出血，鳍侵蚀，肝肿大和脾肿大。在显微镜下，主要发现是肝细胞变性和肝炎，g中的上皮和杯状细胞增生，肾炎，胃炎以及不同器官中存在粘虫样结构。尼罗罗非鱼通过qPCR检测的结果显示，在1号养殖场的被调查鱼中90％的患病率，在2号和2号养殖场的100％中的患病率。这项研究中发现的高患病率表明，这种粘虫动物作为养殖的O. niloticus的潜在病原体的重要性是负面的影响鱼类健康，进而影响产量。