The behavioural response of coral reef fish following introduction to a novel aquarium environment

Abstract

Following the construction of a large-scale public aquarium, we were presented with an opportunity to investigate how wild caught Caribbean reef fish respond to their first encounter with a novel environment. Within the constraints of this opportunity, we designed a behavioural study to determine the reef fishes' response to a new habitat in relation to their locomotory mode. Nine species of fish representing three locomotory modes: carangiform, sub-carangiform and labriform/sub-carangiform were observed over a four-week period following their first introduction to the aquarium. Fish activity levels and spatial distribution were quantified in relation to time since their first encounter with the novel environment. The most important result was that, regardless of locomotory mode or ecology, all of the species extensively explored the novel environment rather than settle on the first habitat that they encountered. This is a particularly interesting result for territorial species. More specifically, however, there were significant differences between species in activity through time. Carangiform activity level was lowest in the initial phases of an encounter with the novel environment subsequently rising to a stable level. The other species had variable activity throughout the study, but all of them exhibited a phase of low activity at some stage during the study. In terms of the fishes' use of the 2.5 million litres of water, six species utilised the whole of the aquarium based on a predefined zoning scheme. Although the initial activity level was low, carangiform swimmers used at least 90% of the zones in the early phases of an encounter with the novel environment and subsequently used all of the zones. Sub-carangiform species also used 100% of the zones by the end of the study. Three of the four labriform/sub-carangiform swimmers used a maximum of 90% of the zones. There was no significant difference between species in their use of the zones. However, each individual zone was subject to differential use by the fish. Owing to the extensive scale of the aquarium, we discuss the applicability of the behavioural results obtained to the natural environment in the context of the ecology of the species of fish studied.