why discus avoid tank lights?

[Dodge]

Noticed my discus always dart to the shaded side when I turn on the tank lights. Got a 75 gallon planted tank with driftwood, temp at 84F, T5HO lights on 8 hours a day. They're about 4 inches, fed beef heart mix twice daily. Anyone else see this behavior? Water params are good, 0 ammonia, 0 nitrite, nitrate around 10ppm.

[Lion]

Mine do the same thing, especially the younger ones. Running a 120 gallon with sand substrate and some floating plants to dim the light. Maybe they're just skittish? I've got a pair of older discus that don't seem to care as much. What's your tank's background color? Darker might help.

[duskfox]

Yo, my discus act like the lights are out to get 'em too. Got a 55 gallon with black background, sponge filter, and some java fern. They chill near the bottom when the lights kick on. Maybe it's a wild instinct thing? Like avoiding predators from above.

[Magpie]

Discus are naturally from shaded, slow-moving waters. Bright lights can stress them. Try reducing intensity or duration. I use LED dimmers on my 90 gallon, and they've gotten more comfortable over time. Also, ensure you're not blasting them with light right after total darkness—gradual sunrise settings help.

[Dodge]

Mine do the same thing, especially the younger ones. Running a 120 gallon with sand substrate and some floating plants to dim the light. Maybe they're just skittish? I've got a pair of older discus that don't seem to care as much. What's your tank's background color? Darker might help.

Thanks, my background's blue, but I'll try adding more floaters. Got some frogbit coming in next week.

[Lion]

Yo, my discus act like the lights are out to get 'em too. Got a 55 gallon with black background, sponge filter, and some java fern. They chill near the bottom when the lights kick on. Maybe it's a wild instinct thing? Like avoiding predators from above.

Wild instinct makes sense. My LFS guy said discus are prey fish in nature, so bright lights might trigger that. Ever tried red lights? Heard they're less stressful.

[duskfox]

Nah, haven't messed with red lights yet. But I did cut my photoperiod to 6 hours, and they seem less jumpy. Also added more driftwood for hiding spots. You guys think tank height matters? Mine's a standard 55, but I've seen taller tanks where they might feel more exposed.

[Magpie]

Height can play a role. In shallow tanks, they might feel more vulnerable. My 90 gallon is 24 inches tall, and they utilize all levels now that they're acclimated. Key is consistency—same light schedule, same feeding times. Sudden changes freak them out more than the light itself.