High fidelity: Assessing zebrafish (Danio rerio) responses to social stimuli across several levels of realism

Selective effects of conspecific movement on social preference in zebrafish (Danio rerio) using real-time 3D tracking and 3D animation

Zebrafish show social behavior such as shoaling and schooling, which is a result of complex and interdependent interactions among conspecifics. Zebrafish social behavior is interdependent in the sense that one fish's behavior affects both conspecific behavior and, as a result, their own behavior. Previous research examined effects of the interdependent interactions on the preference for social stimulus but lacked clear evidence that specific conspecific movements were reinforcing. The present research examined whether dependency between individual experimental fish's motion and a social-stimulus fish's motions contributes to preference for the social stimulus. In Experiment 1, a 3D animated stimulus fish either chased individual experimental fish or was motionless, serving as dependent and independent motions, respectively. In Experiment 2, the stimulus fish either chased experimental fish, moved away, or moved independently of the experimental fish. In both experiments, experimental fish spent more time near the stimulus fish showing dependent and interactive movements, indicating preference for dependent motion over independent motion, and chasing over other motions. Implications of these results are discussed including a potential role of operant conditioning in the preference for social stimuli.

Female zebrafish (Danio rerio) demonstrate stronger preference for established shoals over newly-formed shoals in the three-tank open-swim preference test

Zebrafish (Danio rerio) share a considerable amount of biological similarity with mammals, including identical or homologous gene expression pathways, neurotransmitters, hormones, and cellular receptors. Zebrafish also display complex social behaviors like shoaling and schooling, making them an attractive model for investigating normal social behavior as well as exploring impaired social function conditions such as autism spectrum disorders. Newly-formed and established shoals exhibit distinct behavior patterns and inter-member interactions that can convey the group’s social stability. We used a three-chamber open-swim preference test to determine whether individual zebrafish show a preference for an established shoal over a newly-formed shoal. Results indicated that both sexes maintained greater proximity to arena zones nearest to the established shoal stimulus. In addition, we report the novel application of Shannon entropy to discover sex differences in systematicity of responses not revealed by unit-based measurements; male subjects spent more time investigating between the two shoals than female subjects. This novel technique using established versus newly-formed shoals can be used in future studies testing transgenics and pharmacological treatments that mimic autism spectrum disorder and other disorders that affect social interaction.

Video playback versus live stimuli to assess quantity discrimination in angelfish (Pterophyllum scalare)

Video playback is a widely used technique for presentation of visual stimuli in animal behavior research. In the analysis of behavioral responses to social cues, presentation of video recordings of live conspecifics represents a consistently reproducible stimulus. However, video-recordings do not interact with the experimental subject, and thus this stimulus may be inferior in the social context. Here, we evaluated how angelfish (Pterophyllum scalare) respond to a video playback of conspecifics versus a live shoal of conspecifics. Using binary choice tests, subjects were presented different stimuli. Time spent close to one versus the other stimulus was considered an index of preference. We found angelfish to prefer a live shoal of conspecifics to an empty tank, and also the video playback of a shoal of conspecifics to a blank screen, although the level of preference in the latter was lower than in the former. These results indicate that video-playback of live conspecifics may be appropriate in angelfish, thus allowing manipulation of specific cues that angelfish may use in quantity discrimination. However, when we directly contrasted a live and a video recorded shoal, both having the same number of members, experimental fish preferred the live shoal. When the choice consisted of a live shoal of four conspecifics versus a video playback of a shoal of nine conspecifics no clear preference emerged. These results imply that video-playback has disadvantages in quantity discrimination studies with angelfish. Exploring procedural and/or technological parameters will verify the suitability of video-recording-based stimulus presentation for future use in angelfish.