Vanishing Darkness: How Artificial Light at Night is Badly Rewiring the Aquatic Ecosystems

Artificial light at night (ALAN) has emerged as a pervasive yet often overlooked environmental stressor in aquatic ecosystems. The rapid expansion of urbanization, coastal development, transportation networks, and waterfront infrastructure has substantially increased nocturnal illumination across freshwater and marine habitats, altering natural light-dark cycles to which fish have evolved over millions of years. This short review synthesizes current knowledge on the physiological, behavioural, and ecological consequences of ALAN exposure in fishes. Exposure to artificial lighting can interfere with endocrine signalling, impair orientation and navigation, migration, modify habitat use, and alter species interactions, with potential consequences extending from individual fitness to ecosystem functioning. Collectively, the available evidence highlights ALAN as an increasingly important anthropogenic pollutant that warrants greater consideration in fisheries management, aquatic conservation, and environmental planning. Future research should focus on species-specific responses, long-term ecological effects, and the development of evidence-based lighting guidelines for aquatic environments