Light has positive and negative effects on aquaculture
This article was featured in Eurofish Magazine 1 2025
Aquaculture, one of the fastest-growing segments in food production, constantly seeks innovative strategies to improve the efficiency, health, and sustainability of aquatic farming systems. One promising avenue is understanding the role of light—an often overlooked yet significant factor in influencing the physiology, behaviour, and growth of aquatic organisms.
Two workshops entitled “Light and Fish” and “Light and Other Aquatic Organisms” at last year’s AQUA2024 conference in Copenhagen brought together experts to explore the multifaceted effects of light in aquaculture.
The impact of light is a growing field of study
The AQUA24 workshops, jointly organised by Eurofish (Denmark) and MATE (Hungary), were a continuation of the discussions initiated at the European Aquaculture Society (EAS) 2023 in Vienna. Building on the positive feedback and insights gained previously, the workshops expanded the focus from fish alone to include other aquatic organisms, providing a broader exploration of light’s influence on aquaculture. The sessions were divided into two main themes covering the impact of light on fish and on otheraquatic organisms, and both addressed how various light parameters—such as wavelength, intensity, and photoperiod—affect the physiology, growth, reproductive biology, and health of different species. The sessions featured ten expert-led presentations showcasing advancements in lighting technologies and scientific findings with the potential to transform light use in aquaculture. Key innovations in lighting systems and machine vision were presented, emphasising their role in boosting farming efficiency. Discussions highlighted how specific wavelengths, and light intensities could positively influence fish physiology, impacting feeding behaviours and metabolic rates, with the potential to lower production costs and improve fish welfare.
A major topic centred around light’s role in controlling sexual maturation in aquaculture species. Researchers presented findings showing that targeted light manipulation could suppress melatonin production, delay sexual maturation, and enhance growth rates. Studies demonstrated that continuous light exposure in sea-cage environments led to better growth with further potential for sex-specific light strategies to optimize production. Additionally, the presentations explored emerging LED and supplemental lighting technologies. While these advances offer benefits such as energy efficiency, enhanced production, and parasite management, their long-term effects on fish biology remain only partially understood. Narrow-band lighting, for instance, can impact biological processes beyond growth, potentially leading to outcomes such as stress, premature maturation, or deformities. As light plays a key role in regulating diurnal and seasonal rhythms, developmental stages, and behaviours, careful consideration of light intensity and spectral composition is essential to ensure the well-being of farmed fish.
Some results seem to depend on the wavelength of light
Other sessions focused on the interaction between light, photosynthesis, and oxygen levels, particularly in carp pond systems, where optimised light exposure was shown to improve water quality, boost fish health, and support growth through enhanced photosynthetic activity. Discussions also addressed the effects of light on plankton dynamics, with light enrichment benefiting plankton and oxygen production initially but posing risks to fish health if not balanced correctly. Specific wavelengths also demonstrated promising results in certain species; for example, blue LED light was found to increase growth rates in Malabar grouper, suggesting the potential to enhance growth and reduce feed costs through targeted light use. Moreover, light management strategies were emphasized for improving welfare, especially in smolt and pikeperch farming. Research showed that a 16-hour light and 8-hour dark photoperiod optimized growth and survival in pikeperch larvae, while well-regulated light conditions supported improved feed conversion ratios and growth in fish larvae within recirculating aquaculture systems.
The presentations highlighted a consensus on several key points. Firstly, light is a critical yet underutilised factor in aquaculture production. Despite its proven effects on growth, welfare, and health, the use of light in aquaculture remains in its early stages. The technology is available, but more research is needed to refine how different species respond to varying light conditions, including intensity, duration, and wavelength. Participants agreed to try and reorganise these discussions as sessions at the upcoming EAS 2025 in Valencia. By integrating these workshops into a larger platform, the organisers hope to further the discourse, facilitate collaboration, and ultimately develop comprehensive guidelines for light management in aquaculture.
When combined with other modern technologies, light shows even more promise
By integrating advanced technologies like AI and machine vision, as well as drawing on natural processes such as photosynthesis, the aquaculture industry stands at the cusp of a new era where light becomes a cornerstone of sustainable and efficient fish production. As the field progresses, workshops like those at AQUA24 will be instrumental in shedding light on the complex interplay between light and life in aquatic environments—paving the way for innovations that benefit both producers and the environment.
Eva Kovacs, Eurofish,
eva@eurofish.dk; Christian P. Unmack, Eurofish,
christian@eurofish.dk