Survival and respiration of marbled rabbitfish (Siganus rivulatus) fingerlings at various oxygen tensions

Résumé 0

Marbled rabbitfish, Siganus rivulatus, is an economically valuable herbivorous fish and a potential candidate for warmwater aquaculture. This study was carried out to: (1) assess the effect of various oxygen concentrations on survival and behaviour of S. rivulatus fingerlings and (2) investigate the response of S. rivulatus to hypoxia and determine its critical oxygen tension (Pcrit). In the first experiment, groups of rabbitfish (15 fish per group) were maintained for 1 h in waters of various oxygen concentrations. They were then transferred to well-aerated tanks and observed for 72 h. Survival was recorded, fish behaviour at low oxygen concentrations observed, and LC50 after 1-h hypoxia and 72-h recovery evaluated. In the second experiment, a series of stop-flow respirometry experiments were performed during which dissolved oxygen was allowed to drop to 0.5 mg L−1 and respiration rate recorded at various oxygen concentrations. In the first experiment, all fish survived for 1 h at oxygen concentration of 1.44 mg L−1 and greater, but started dying at oxygen concentrations below 0.65 mg L−1 (16% survival). The LC50 of S. rivulatus fingerlings was 0.6 mg L−1. Results of the second experiment showed that S. rivulatus is an oxyregulator until Pcrit (1.7 mg L−1 O2) is reached, becoming an oxyconformer below this concentration. Findings allow for a better understanding of environmental oxygen tolerances and minimum acceptable oxygen concentration in rabbitfish aquaculture. © 2016 John Wiley & Sons Ltd