Seasonal dynamics of Dactylogyrus species (Monogenea: Dactylogyridae) on wild and farmed goldfish (Carassius auratus): Implication for prevention of dactylogyriasis

Abstract

Dactylogyrid is the common parasite on the gills of goldfish (Carassius auratus). Seasonal dynamics of the dactylogyrids on goldfish were investigated from March 2011 to February 2012 in the Liangzi Lake and a fish pond in Shishou, China. Six Dactylogyrus species were found, i.e. D. vastator, D. intermedius, D. arcuatus, D. baueri, D. formosus and D. inexpectatus. The highest mean abundance was recorded for D. arcuatus (4.39) on the wild goldfish, while the highest for D. vastator (0.27) on the farmed goldfish. In Liangzi Lake, except for D. inexpectatus with low infection, prevalence and mean abundance of the other five species of Dactylogyrus exhibited significant seasonal changes (P < 0.05). Three seasonal patters were observed, three peaks in spring, summer and autumn, such as D. vastator; two peaks in winter and summer, such as D. formosus; one peak in spring, such as D. intermedius, D. arcuatus and D. baueri. Despite of the different seasonal patters, high prevalence and mean abundance were observed for D. vastator, D. intermedius, D. arcuatus and D. formosus in February or March with low water temperature. In the pond, only the D. vastator exhibited high prevalence and mean abundance, and similar seasonal dynamic as that in the lake, which suggested that it was appropriate to prevent and control disease caused by D. vastator in February in goldfish farming.