Betta fish don’t need constant light at night—instead, they require a dark environment to ensure proper rest and physiological health. Here’s a detailed breakdown:
1. Betta Fish’s Physiological Needs and Natural Habits
Circadian Rhythm: As tropical fish, bettas are adapted to natural day-night cycles. A dark nighttime environment helps them enter a resting state and maintain normal physiological rhythms.
Sleep Behavior: Bettas reduce activity at night, resting on the tank bottom or among aquatic plants. Constant light disrupts this behavior, triggering stress responses like restlessness and decreased appetite.
Vision Adaptation: While bettas can move in low light (relying on their lateral line system to detect water flow and vibrations), prolonged exposure to bright light damages their eyesight and impairs overall health.
2. Negative Impacts of Constant Nighttime Light
Sleep Deprivation: Light inhibits melatonin secretion (the hormone regulating sleep) in bettas, leading to insufficient sleep. This lowers immunity and increases disease risk.
Abnormal Behavior: Bettas exposed to long-term light stimulation may exhibit hyperactivity, increased aggression, or hiding behaviors, reducing their quality of life.
Water Quality Issues: Light promotes algae growth. Without timely tank cleaning, algae overgrowth can deteriorate water quality, indirectly endangering betta health.
3. Recommendations for Proper Light Management
Simulate Natural Cycles: Provide 8–12 hours of light daily (LED lights work well), then turn off all light sources at night. Alternatively, use a timer for automatic control.
Avoid Direct Bright Light: Choose soft lighting (e.g., blue night lights) to minimize stimulation. If the tank is in a naturally bright area, use a light-blocking cloth to adjust.
Monitor Betta Responses: If your betta swims frequently or hides at night, the light may be too bright or on for too long—adjust the lighting plan accordingly.
4. Handling Special Cases
Breeding Period Needs: Males require faint light (e.g., low-wattage LEDs) while building bubble nests, but the tank should still stay dark at night to avoid disrupting breeding behavior.
Disease Treatment: If 24-hour light is needed for treatment (e.g., for ich), shorten the treatment period and restore the day-night cycle once the betta recovers.