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I've got a 75-gallon tank with 8 adult Discus, a school of 12 Cardinal Tetras, and 6 Corydoras. The fish seem active, but I'm worried about space. Water params are stable, 0 ammonia, 0 nitrite, 5 nitrate, pH 6.8. Temp's at 84°F with a Fluval FX6 running. Anyone think this is pushing it?

Dude, that sounds tight. I ran a similar setup once and my Discus got mad stressed. They started hiding behind the driftwood all day. Maybe cut it back to 6 Discus? Tetras and Corys are chill but they add up.

The bioload seems manageable with your filtration, but Discus need swimming space. Are they showing aggression or staying in one spot? My 90-gallon has 6 Discus, and even that feels full when they're all adults.

Boldly wrote: ↑Sat May 31, 2025 9:30 am Dude, that sounds tight. I ran a similar setup once and my Discus got mad stressed. They started hiding behind the driftwood all day. Maybe cut it back to 6 Discus? Tetras and Corys are chill but they add up.

Agreed. Overcrowding can mess with their growth long-term. What's your water change routine? Frequent changes might help if you're stuck with the current stock.

I'd watch for fin nipping. Crowded Discus can get territorial, especially during feeding. How's their appetite? If they're eating well and not fighting, you might be okay, but it's sketchy long-term.

Yo, my LFS guy swears by 10 gallons per Discus minimum. Your tank's on the edge, but if you're doing 50% water changes weekly, it could work. Just keep an eye on their behavior.

Thanks for the input, everyone. I do 50% water changes twice a week, and they're eating like crazy. No aggression yet, but I'll monitor closely. Might rehome a couple if I see issues.

The Tetras and Corys aren't the issue, but 8 adult Discus is a lot for 75 gallons. They'll grow more, and space will shrink. Consider upgrading or reducing stock before it's a problem.

My 75 has 5 Discus, 10 Rummy Noses, and 4 Corys. Even that feels packed when they're all active. Your setup's doable but not ideal. Watch for stress bars on the Discus.

Cloudy wrote: ↑Sat May 31, 2025 12:22 pm

Boldly wrote: ↑Sat May 31, 2025 9:30 am Dude, that sounds tight. I ran a similar setup once and my Discus got mad stressed. They started hiding behind the driftwood all day. Maybe cut it back to 6 Discus? Tetras and Corys are chill but they add up.

Agreed. Overcrowding can mess with their growth long-term. What's your water change routine? Frequent changes might help if you're stuck with the current stock.

Second this. More water changes could buy time, but it's a band-aid. Long-term, fewer fish or bigger tank.