Do the Anemonefish Amphiprion ocellaris (Pisces: Pomacentridae) Imprint Themselves to Their Host Sea Anemone Heteractis magnifica (Anthozoa: Actinidae)?

Abstract Juvenile anemonefishes detect their host sea anemone by olfactory stimuli; in order to investigate whether this behaviour is innate or acquired, the anemonefish species Amphiprion ocellaris was bred in two different ways: 1. With no host sea anemone present at all (–A); and 2. With the specific host sea anemone Heteractis magnifica present in the hatching aquarium, so that these eggs were laid and hatched close to the sea anemone, as in nature (+A). The two different types of juvenile A. ocellaris were presented to the odours of the host sea anemone H. magnifica in two sets of short‐term experiments with the host (a) visually hidden in a net cage, and (b) visible but physically separated from the anemonefishes. In both cases, a water flow was established between fishes and host. The +A‐fishes found their host by olfactory and not by visual stimuli. In both series, the –A‐fishes showed a significantly lower affinity behaviour towards the odour compounds from the host sea anemone than the +A‐fishes did. A third type of experiment was a direct confrontation between fishes and host; here, the –A‐fishes were indifferent towards the host sea anemone for almost 48 h, while the +A‐fishes acclimated to the host sea anemone within the first 5 min of the direct confrontation. The results of this study suggest that Amphiprion ocellaris imprints itself olfactorily to its species‐specific host sea anemone Heteractis magnifica , and, furthermore, may be genetically disposed towards olfactory recognition of the host sea anemone.