Fisheries Research Articles

Document Type

Article

Publication Date

2-2026

Journal Title

Aquaculture Nutrition

ISSN

1365-2095

Keywords

aquaculture, cineole, nanoemulsion, pharmacokinetics, rosemary oil, Seriola lalandi, Zeuxapta seriolae

Disciplines

Aquaculture and Fisheries

Abstract

This study evaluated the anthelmintic efficacy of rosemary oil delivered as a nanoemulsion compared with regular rosemary oil against the monogenean parasite Zeuxapta seriolae in yellowtail kingfish (YTK; Seriola lalandi). A 20-day feeding trial tested three dietary treatments: two levels of regular rosemary oil (providing 0.85 and 1.7 g cineole·kg−1 feed) and a rosemary-oil nanoemulsion (providing 0.85 g cineole·kg−1 feed), against a control diet without rosemary oil. Juvenile fish (293 ± 5 g) were pre-exposed to Z. seriolae oncomiracidia before the trial, resulting in an initial mean parasite abundance of 97 ± 4 per fish. At trial completion, plasma cineole concentrations were highest in fish receiving the high-dose regular rosemary oil diet, followed by the nanoemulsion diet, and then the low-dose regular rosemary oil. These plasma levels closely matched treatment efficacy: fish fed the high-dose diet exhibited the lowest mean abundance of Z. seriolae, followed by those receiving the nanoemulsion and low-dose diets. A similar pattern was observed for juvenile parasite recruitment. Across parasite developmental stages, all rosemary-oil treatments significantly reduced the proportion of juvenile Z. seriolae relative to the control. Growth performance and feed intake did not differ among treatments. Plasma biochemistry remained unchanged, and no histopathological alterations were detected in liver or kidney tissues. Overall, these findings demonstrate that dietary rosemary oil effectively transfers cineole into the blood of YTK and reduces Z. seriolae infection and that application of the rosemary oil in a nanoemulsion further increases cineole uptake.

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