- Circadian Rhythm Disruption: Constant exposure to light disrupted fish circadian rhythm, leading to chronic stress. Stress can weaken immune system, making the fish more susceptible to diseases and infections.
- Disrupted sleep patterns: Fish need periods of darkness to sleep and rest, just like humans. Constant light deprives them of essential rest, leading to fatigue, reduced activity and impaired cognitive functions.
- Stress: Constant light can cause stress in fish, leading to changes in behavior, such as increased hiding and reduced exploration, as they may feel vulnerable and exposed without periods of darkness.
- Altered Melatonin Production: Light affects melatonin production, a hormone that regulates sleep and wake cycles. Constant light suppresses melatonin production, disrupting fish natural sleep- wake cycles.
- Impaired Immune System: Prolonged stress from constant light can weaken their immune system, increasing the risk of diseases.
- Altered Behavior: Fish may display abnormal behaviors, such as erratic swimming, avoidance of certain areas of the tank, and loss of appetite.
- Impaired Reproduction: In some species, constant light can disrupt reproduction by interfering with hormone production and mating behaviors.
- Visual Damage: Some fish have sensitive eyes and constant bright light can cause damage to their retinas.
- Algae Growth: Continuous light promotes algae growth in the aquarium, which can become unsightly and compete with plants for nutrients and sunlight.
Therefore, it's essential to provide fish with a dark period each day to ensure their overall well-being. A recommended light schedule for most aquarium fish is approximately 10-12 hours of light per day, followed by 12-14 hours of darkness.