Stress: Why Lighting Matters
October 31, 2025
During our recent visit to Queen Mary University of London, Sue Keefe made a comment that really resonated with our team:
“Our zebrafish are a lot calmer when held under ZebLED dedicated tank lighting. You can move past the tank, and the aren’t as skittish.”
This simple observation captures something profound.
When lighting is tuned to match the visual sensitivity of the animal, it has a measurable impact on behaviour, welfare, and wellbeing.
Put simply — when animals see light in the wavelengths they naturally perceive, they remain calm and comfortable. Get it wrong, and stress follows. Light outside their visual range creates unnatural shadows and distortion, triggering a “fight or flight” response.
At Biosystems, we’ve seen this consistently across species — from fish, sharks, and corals to chickens, pigs, and now zebrafish. The results are clear:
- Reduced stress
- Improved welfare and health outcomes
- Enhanced breeding performance
Lighting isn’t just illumination — it’s a biological signal.
By aligning the spectrum, intensity, and photoperiod with an animal’s native environment, we can directly influence behavioural stability, circadian rhythm entrainment, and endocrine balance.
- Spectrum: Matching spectral output to species-specific visual sensitivity reduces visual strain, reducing stress, feed provision and aggression.
- Photoperiod: Correct day-night cycles improve breeding synchronisation and larval development.
- Low-level dimming & control: Smooth transitions between low light and full light states mimic natural dawn and dusk, avoiding startle responses and stress peaks.
Lab vs. Culture Lighting
In research facilities, laboratory lighting often conflicts with the benefits of dedicated culture lighting.
Our work highlights the importance of managing light spillover, reflection, and spectral differences between human centric observer environments and holding systems — ensuring that human convenience doesn’t compromise animal welfare.
Implications for Zebrafish Research
Zebrafish are particularly sensitive to photic environment.
By applying principles refined in aquaculture and zoological systems, we’ve developed lighting strategies that:
- Stabilise behavioural assays,
- Support reliable breeding cycles
- Improve long-term welfare metrics.
Because healthier fish yield better science.