Comparative biochemistry and physiology. Toxicology & pharmacology : CBPAug 1, 2026

Artificial light at night affects early development and behavior in young zebrafish

Circadian Biology Weekly Brief ↗PubMed ↗DOI ↗

Updated Aug 3, 2026

Abstract

Zebrafish embryos exposed to artificial light at night (ALAN) showed increased heart rates and reduced eye area under certain light conditions.

ALAN exposure did not significantly affect survival rates, hatching time, or blood flow velocity in zebrafish embryos.
Increased heart rates were observed at light intensities of 75 and 225 lx at 48 hours post-fertilization.
A progressive reduction in eye area was noted, along with decreased optokinetic response in zebrafish exposed to ALAN.
Locomotor activity decreased and anxiety-like behavior was induced in zebrafish larvae following ALAN exposure.
Biochemical analysis indicated significantly lower levels of dopamine and its metabolites, correlating with observed physiological and behavioral deficits.
Visual deficits from ALAN exposure were linked to behavioral changes in zebrafish larvae.

Simplified

Artificial light at night (ALAN), a form of physical pollution with growing global impacts, has been shown to induce various adverse effects on terrestrial organisms. However, studies on the effects of ALAN on aquatic organisms, particularly fish during early life stages, remain limited. In this study, zebrafish embryos were exposed to ALAN at 0, 25, 75, and 225 lx until 144 hours post-fertilization (hpf) with manipulated circadian cycles (light/dark or light/ALAN) to assess alterations in development, survival, behavior, and the monoaminergic system. The results showed that ALAN exerted no significant effects on the survival rate, hatching time, or blood flow velocity (at 72 hpf) of zebrafish embryos/larvae, but increased the embryonic heart rate (at 48 hpf) under the 75 and 225 lx conditions. Concurrently, the eye area of zebrafish exhibited a progressive reduction, accompanied by a decreased optokinetic response (OKR). Moreover, ALAN exposure decreased locomotor activity and induced marked anxiety-like behavior in zebrafish larvae. Biochemical analysis revealed significantly decreased levels of DA and its metabolites in zebrafish, which were associated with the observed physiological and behavioral deficits. In addition, the visual deficits induced by ALAN were closely linked to the behavioral alterations in zebrafish larvae. In summary, ALAN exposure is closely linked to the dopaminergic pathway, which correlates with disrupted early-life development and behavioral impairments in zebrafish. These findings highlight the potential risks that nocturnal light pollution poses to aquatic ecosystems, particularly in urbanized areas.

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Artificial light at night affects early development and behavior in young zebrafish

Abstract

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