Fish from the same species can evolve their sense of smell and display individual foraging 'personalities' to successfully find food in different habitats, according to new research. In the study, published today as a Reviewed Preprint in eLife, researchers developed a high-throughput behavioural assay to test spontaneous swimming and differences in the sense of smell of individual Mexican cavefish larvae.

eLife editors described the work as important, presenting compelling evidence that the surface and cave morphs of the fish show different olfactory preferences and odour sensitivities, and that individual fish show substantial variability in their spontaneous activity that is relevant for olfactory behaviour.

With more than 26,000 species representing half of all vertebrates, bony fishes are extremely diverse and have colonised all possible ecological niches, through their ability to adapt their sensory systems. Yet, although the comparative anatomy of fish brains is well documented, behavioural studies have mainly focused on a few model species such as zebrafish. The links between how fish sensory systems evolve and resulting fish behaviour remain poorly understood and hinder cross-species comparisons.