The introduction of myxozoan parasites through the release of feeder goldfish (Carassius auratus)

Myxozoa have been found worldwide; these parasites infect a wide variety of\ud hosts, but have been found most often in fish. Carassius auratus (goldfish), a popular\ud aquarium fish and a widespread invasive species, have been identified as an intermediate\ud host for several myxozoan species. Some myxozoan parasites are pathogenic and can\ud lead to the death of the fish host; others merely decrease the market value of the fish due\ud to unsightly cysts. Goldfish from three different types of sites were sampled— rearing\ud facilities, pet shops, and natural waterways, in order to assess the potential for the\ud introduction of myxozoan parasites to the environment through the pet shop trade. Four\ud different Myxozoa were identified via their morphology and morphometrics: Myxobolus\ud cultus, Myxobolus diversus, Sphaerospora sp., and Hoferellus carassii. The four\ud myxozoan species detected were previously identified; the data indicates a seasonal\ud variation in myxospore presence, more data collection is needed for conclusive results.\ud This survey showed that feeder goldfish can introduce novel Myxozoa to natural\ud waterways, although whether the Myxozoa can establish an infectious cycle in those\ud waterways is unknown. If the Myxozoa can establish an infectious cycle, they could have\ud a serious impact on fish residing in those waterways