Social ties are maintained through sensory adaptations in green chromides

Sensory systems exhibit considerable plasticity in response to environmental changes, yet the functional implications of such plasticity remain poorly understood, particularly regarding how changes in visual gene expression influence social behaviour. To address this gap, we investigated how visual sensory plasticity relates to conspecific preferences in green chromides (Etroplus suratensis), an Indian cichlid that relies on vision for social preferences towards conspecifics. We first characterized retinal opsin and chromophore-related genes through transcriptomic analysis and subsequently examined behavioural and molecular responses under sequential white- and blue-light environments. We quantified visually mediated conspecific preferences, and the expression of rod and cone opsins and the chromophore-related gene Cyp27c1 at regular intervals. Green chromides retained stable conspecific preferences despite contrasting light environments. Opsins exhibited plasticity, with long wavelength-sensitive opsin (LWS) increasing under blue light, whereas short wavelength-sensitive opsins remained unchanged. Additionally, Cyp27c1 expression declined under blue light, suggesting a potential shift towards increased A1 chromophore utilization. Together, these findings suggest that green chromides undergo multiple molecular modifications under contrasting light environments, whereas maintaining stable social behaviours, demonstrating the cross-talk between the two is not straightforward. Overall, these results highlight that unraveling the underlying proximate mechanisms of behavior is highly intricate, involving multiple pathways, starting from perception (at the retinal level) to post-processing of the stimulus.