Proliferative gill disease (PGD) caused by the myxozoan Henneguya ictaluri is one of the most damaging diseases affecting U.S. catfish aquaculture. In channel and hybrid catfish, continuous exposure to the actinospore stage of the parasite elicits a destructive branchitis, impairing osmoregulatory and respiratory function. Mortality can reach 100% in severe outbreaks. Despite similarities during acute stages of infection, research indicates arrested development in hybrid catfish, evinced by reduced H. ictaluri sporogenesis and comparably less parasite DNA in hybrid tissues across the developmental timeline. To assess these findings at the pond level, 18, 0.4‐ha ponds were stocked (3,000 fish/pond) with channel (n = 9) or hybrid (n = 9) catfish fingerlings and maintained as monoculture systems for three production cycles, with clean harvests and restocking as warranted. Water was collected monthly for quantitative polymerase chain reaction (qPCR) estimations of H. ictaluri DNA, and sentinel fish were utilized to estimate PGD severity. By the second year, H. ictaluri DNA in hybrid systems was significantly reduced, and PGD lesions in sentinel fish were negligible. Assessment of parasite loads in fish harvested at the termination of the study revealed H. ictaluri DNA in channel catfish to be an order of magnitude higher than hybrid catfish. These results support previous work suggesting that the production of hybrid catfish may reduce PGD incidence in U.S. catfish aquaculture.

中文翻译：

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♀鱼（Ictalurus punctatus）×♂蓝色（I. furcatus）杂交cat鱼的单种养殖减轻了a鱼水产养殖池塘中由Henneguya ictaluri（Cnidaria：Myxobolidae）引起的增殖性ill病。

由粘虫Henneguya ictaluri引起的增生性ill病（PGD）是影响美国cat鱼养殖的最具破坏性的疾病之一。在沟cat和杂种cat鱼中，持续暴露于该寄生虫的放线孢子期会引发破坏性分支炎，损害渗透调节和呼吸功能。严重暴发时死亡率可达到100％。尽管在急性感染阶段有相似之处，但研究表明，杂交cat鱼的发育停滞，这是由于在整个发育过程中，杂种H. ictaluri孢子形成减少，杂种组织中的寄生虫DNA相对较少所致。为了在池塘一级评估这些发现，在18个0.4公顷的池塘中放养（3,000条鱼/池塘），其中池塘（n = 9）或杂种（n= 9）fish鱼鱼种并作为单一养殖系统进行了三个生产周期的维护，保证了收成干净和放养。每月收集一次水，用于对鱼嗜血菌DNA进行定量聚合酶链反应（qPCR）评估，并利用前哨鱼评估PGD的严重程度。到第二年，杂种系统中的菌DNA显着减少，前哨鱼中的PGD损伤可忽略不计。对研究结束时收获的鱼中寄生虫负荷的评估显示，channel鱼中的ic鱼嗜血杆菌DNA比杂交cat鱼高一个数量级。这些结果支持以前的工作，表明杂种cat鱼的生产可能会降低美国cat鱼水产养殖中的PGD发生率。