Who Gives A Fish Forums

My discus tank is sitting at 86°F, but they seem stressed. Water params are good, 0 ammonia, 0 nitrite, 10 nitrate. Tank is 75 gallons, planted with driftwood, and I do 30% water changes twice a week. Should I lower the temp?

86°F is pushing it, mate. Discus can handle warm water, but that's like a sauna for 'em. Mine chill at 82°F, and they're thriving. What's your heater brand? Some of those cheap ones are sketchy with temp swings.

foxcape wrote: ↑Wed Jun 11, 2025 12:25 pm 86°F is pushing it, mate. Discus can handle warm water, but that's like a sauna for 'em. Mine chill at 82°F, and they're thriving. What's your heater brand? Some of those cheap ones are sketchy with temp swings.

Agreed. I've kept Discus for years, and 82–84°F is the sweet spot. Higher temps can mess with their metabolism. What's your feeding routine? Overfeeding in warm water can spike ammonia fast.

Yep, 86°F is too toasty. My crew hangs at 83°F, and they're solid. You got a backup thermometer to double-check? Those digital ones can be wonky. Also, what's your tank's flow like? High flow + high heat = stressed fish.

I'd lower it slowly, like 1°F per day. Sudden drops freak 'em out. Your plants might struggle too if it's too warm. What kind of substrate are you using? Some hold heat weirdly.

Mango wrote: ↑Fri Jun 13, 2025 6:05 am I'd lower it slowly, like 1°F per day. Sudden drops freak 'em out. Your plants might struggle too if it's too warm. What kind of substrate are you using? Some hold heat weirdly.

Good point. Sand can trap heat, especially if it's deep. How's your lighting schedule? Longer photoperiods + high heat can cause algae blooms.

My tank's at 84°F, and the discus are vibing. You got any tankmates? Some fish can't handle the heat, and that might be adding stress.

86°F is wild, dude. Mine are happy at 83°F with a canister filter and weekly water changes. What's your filter setup? Poor filtration + heat = bad news.

Thanks for the advice, everyone. I'll dial it back to 83°F and monitor. Heater's a Fluval E300, and I've got a backup thermometer coming tomorrow.

Rider wrote: ↑Fri Jun 13, 2025 11:06 am Thanks for the advice, everyone. I'll dial it back to 83°F and monitor. Heater's a Fluval E300, and I've got a backup thermometer coming tomorrow.

Smart move. Fluval's decent, but always good to verify. How often do you clean your filter media? Clogged media can cause temp swings.