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Since the use of malachite green was banned, it is desirable to search for alternative drug to control Ichthyophthirius multifiliis infection. Moreover, route of administration which is easy to implement and less stressful to fish is important to treat infection of fish with this parasite. It is also important to enhance protective effect against Aeromonas hydrophila infection after parasitism by I. multifiliis. The present study evaluated the protective effect of diet supplemented with Artemisia annua against I. multifiliis and A. hydrophila infection after the parasitism. The results showed that oral administration with A. annua at a concentration of 20 g/kg feed for 45 days can provide strong protection against I. multifiliis infection. The incidence of infestation and mean number of trophonts on fish fins on day 3 post-challenge (15,000 theronts/fish) were significantly reduced compared with the control, and the survival rate of fish during 15-day period was also increased by nearly 30 %. But, this diet provided very limited protection against higher infection dose. Besides, this study demonstrated that this diet enhanced protective effect against A. hydrophila after the fish were infected with I. multifiliis. On the basis of the above results, oral administration with A. annua can be used as a potential strategy for control I. multifiliis infection and increasing fish survival after parasitism by I. multifiliis. [ABSTRACT FROM AUTHOR]

Goldfish, Carassius auratus, widely distributed across Eurasia, is one of the earliest fish domesticated for ornamental purposes. A series of diseases break out due to high-density culture of goldfish, causing significant economic losses. Here, we report for the first time an infection of Gyrodactylus kobayashii associated with the high mortality of goldfish from a fish farm in Anziying township of Henan province, China, following their transfer to several aquariums. In the first 2 weeks after goldfish ( n = 4200, weight 10.24 ± 1.45 g) transfer to aquariums, a total of 3335 goldfish were lost, representing 79.4 % of the initial stocked biomass. The examination showed that no other pathogens were found in this batch of fishes, except for G. kobayashii. The high burdens of G. kobayashii/fish (264.7, range 100-450) were the primary reason for the high mortality, although this was not the sole cause. In addition, the isolate of G. kobayashii from goldfish ( C. auratus) in Henan province of central China was described. The morphological characterization was performed using morphometric measurements and drawings of opisthaptoral hard parts of the parasites. The molecular description was performed based on phylogenetic analysis of a reference DNA sequence spanning 5.8S and ITS-2. Importantly, the present study provides for the first time a full 25 point-to-point morphometric measurements and high-resolution images of attachment organ of G. kobayashii. [ABSTRACT FROM AUTHOR]