Received: 24 July 2018 Accepted: 22 January 2019 DOI: 10.1111/jfb.13910 FISH SYMPOSIUM SPECIAL ISSUE REGULAR PAPER Host choice and fitness of anemonefish Amphiprion ocellaris (Perciformes: Pomacentridae) living with host anemones (Anthozoa: Actiniaria) in captive conditions Hai-Thanh T. Nguyen1,2 | A-Nga T. Tran2 | Le Thi L. Ha3 | Dang N. Ngo2 | Binh T. Dang2 | Audrey J. Geffen1 1Department of Biological Sciences, University of Bergen, Bergen, Norway In this study, we investigated the host choice of naïve Amphiprion ocellaris, a specialist, at two dif- 2Institute of Biotechnology and Environment, ferent stages of development (newly settling juveniles and post-settlement juveniles). The fish Nha Trang University, Nha Trang, Vietnam were exposed to their natural and unnatural host species in the laboratory and their fitness was 3Aquatechnology Department, Institute of assessed in terms of activity and growth rate. Newly settling juveniles exhibited little host prefer- Oceanography, Nha Trang, Vietnam ence, while post-settlement juveniles immediately associated with their most common host in the Correspondence wild. The analysis of fish activity confirmed that A. ocellaris is diurnal; they are most active in the Hai-Thanh T. Nguyen, Institute of Biotechnology and Environment, Nha Trang morning, less at midday and barely move at night. The average travelling distance of juveniles was University, 02 Nguyen Dinh Chieu, Nha Trang, shorter in the groups living with their natural host, increasing in the groups living with an unnatu- Khanh Hoa, Vietnam. ral host and was highest in groups that did not become associated with any other unnatural host Email:
[email protected] species. Post-settlement juveniles living with the natural host species grew better than those living Funding information with unnatural hosts or without anemone contact.