Who Gives A Fish Forums

Noticed my discus darting behind plants whenever the tank light turns on. They're in a 75-gallon with sand substrate, driftwood, and Amazon swords. Water's at 84°F, pH 6.8, 0 ammonia, 0 nitrite, 10 nitrate. Using a Fluval 3.0 light on a 10-hour cycle. Anyone else deal with this?

Yo, same issue here. Mine chill in the shadows till lights dim. Got a 55-gallon with blackwater setup, tannins dark as coffee. Try cutting the light intensity or duration, bro. My Fluval's at 50% for 8 hours now, and they're way less sketchy.

Mine do that too! 60-gallon with sponge filter, temp at 86°F. They hide under the driftwood like it's a game. Maybe they're just drama queens?

vital wrote: ↑Thu Jun 19, 2025 5:25 pm Yo, same issue here. Mine chill in the shadows till lights dim. Got a 55-gallon with blackwater setup, tannins dark as coffee. Try cutting the light intensity or duration, bro. My Fluval's at 50% for 8 hours now, and they're way less sketchy.

Solid advice. I dropped my Nicrew to 6 hours and added floating plants. Now they're out more, munching on beef heart like it's a buffet.

Discus are low-light river fish in the wild. Your setup's too bright. Reduce intensity to 30-40%, add tall plants like vals for shade. My 90-gallon has dim LEDs on a sunrise/sunset timer, zero hiding issues.

Mine used to bolt when lights hit. Switched to a Finnex planted+ 24/7 mode, which mimics natural light cycles. Now they're out all day in my 120-gallon, even with the rays shining. Maybe try gradual changes?

guyah wrote: ↑Thu Jun 19, 2025 9:25 pm Discus are low-light river fish in the wild. Your setup's too bright. Reduce intensity to 30-40%, add tall plants like vals for shade. My 90-gallon has dim LEDs on a sunrise/sunset timer, zero hiding issues.

Exactly this! Wild discus avoid direct light. My tank's got duckweed covering 70% of the surface, and they're way more active now. 82°F, weekly 50% water changes.

Check your light spectrum too. Blue-heavy LEDs freak them out. I use a warmer 6500K bulb in my 75-gallon, and they don't even flinch at lights-on anymore. Also, feed them right after lighting up—distracts them from the change.

Thanks, all! Gonna tweak the Fluval settings and grab some floaters this weekend. Appreciate the tips.

Light stress triggers cortisol spikes. Documented in studies. Your Fluval 3.0's PAR values are excessive for discus. Set it to 30% max, 6-hour photoperiod. Add Indian almond leaves for shade. 75-gallon should have at least 50% cover.