is discus tank too crowded?

Chat about all things related to Discus, from purchasing to breeding and everything in between. One of the most beautiful species in the hobby
User avatar
jolvy
Posts: 16
Joined: Sun Feb 13, 2022 5:51 am

is discus tank too crowded?

Post by jolvy »

I've got a 75-gallon tank with 8 adult Discus, a school of 12 Cardinal Tetras, and 6 Corydoras. The Discus are around 5-6 inches each. I do 50% water changes twice a week, pH is stable at 6.5, temp at 84°F. They seem fine but I'm worried about space. Am I pushing it?
Ticgo
Posts: 26
Joined: Thu Oct 10, 2024 3:33 pm

Re: is discus tank too crowded?

Post by Ticgo »

That sounds like a solid setup, but 8 Discus in a 75 might be tight long-term. They're big swimmers, and stress can creep up. How's their behavior? Any aggression or hiding? I'd watch for signs like clamped fins or lack of appetite.
vimster
Posts: 23
Joined: Mon Sep 25, 2023 12:04 am

Re: is discus tank too crowded?

Post by vimster »

jolvy wrote: Tue Sep 16, 2025 4:52 pm I've got a 75-gallon tank with 8 adult Discus, a school of 12 Cardinal Tetras, and 6 Corydoras. The Discus are around 5-6 inches each. I do 50% water changes twice a week, pH is stable at 6.5, temp at 84°F. They seem fine but I'm worried about space. Am I pushing it?
Technically, you're at the upper limit. The general rule is 10 gallons per adult Discus, but your water change routine is excellent. If they're not showing stress, you might be okay, but I'd consider upgrading if you notice any issues. Also, keep an eye on nitrates—they can spike faster in a stocked tank.
vimster
Posts: 23
Joined: Mon Sep 25, 2023 12:04 am

Re: is discus tank too crowded?

Post by vimster »

jolvy wrote: Tue Sep 16, 2025 4:52 pm I've got a 75-gallon tank with 8 adult Discus, a school of 12 Cardinal Tetras, and 6 Corydoras. The Discus are around 5-6 inches each. I do 50% water changes twice a week, pH is stable at 6.5, temp at 84°F. They seem fine but I'm worried about space. Am I pushing it?
Technically, you're at the upper limit. The general rule is 10 gallons per adult Discus, but your water change routine is excellent. If they're not showing stress, you might be okay, but I'd consider upgrading if you notice any issues. Also, keep an eye on nitrates—they can spike faster in a stocked tank.
SlateFang
Posts: 13
Joined: Thu Oct 10, 2024 3:41 pm

Re: is discus tank too crowded?

Post by SlateFang »

Yo, that's a packed house! I ran 6 in a 75 and even that felt sketchy. They need room to flex, ya know? If they're chill now, cool, but don't push it. Maybe cut back on the tetras if things get weird.
User avatar
dayton
Posts: 15
Joined: Thu Oct 10, 2024 4:10 am

Re: is discus tank too crowded?

Post by dayton »

I've got a similar setup, 7 Discus in an 80-gallon with Rummy Noses. Key is filtration—I run dual canisters and a sponge. If your water's pristine and they're eating like pigs, you're probably fine. But yeah, watch for nipping or lethargy.
landfall
Posts: 11
Joined: Thu Oct 10, 2024 3:40 pm

Re: is discus tank too crowded?

Post by landfall »

Ticgo wrote: Wed Sep 17, 2025 7:07 pm That sounds like a solid setup, but 8 Discus in a 75 might be tight long-term. They're big swimmers, and stress can creep up. How's their behavior? Any aggression or hiding? I'd watch for signs like clamped fins or lack of appetite.
Spot on. Also, Discus are social but need their space. If they start staking out corners or darting, it's a red flag. My crew got moody in a 75, so I upgraded to a 120. Night and day difference.
User avatar
angelic
Posts: 23
Joined: Sun Jun 16, 2024 5:46 pm

Re: is discus tank too crowded?

Post by angelic »

Your water change routine is commendable, but crowding can still cause subtle stress. Discus secrete hormones that build up, even with clean water. If you can't upgrade, consider adding more plants or driftwood to break sightlines and give them zones. Floating plants like Frogbit can help too.
purered
Posts: 19
Joined: Thu Oct 10, 2024 6:22 pm

Re: is discus tank too crowded?

Post by purered »

Man, I'd be sweating with that many big fish in there! My rule is 1 Discus per 15 gallons if you wanna keep it comfy. But hey, if they're vibing and your water's on point, roll with it. Just stay sharp on those water changes.
purered
Posts: 19
Joined: Thu Oct 10, 2024 6:22 pm

Re: is discus tank too crowded?

Post by purered »

Man, I'd be sweating with that many big fish in there! My rule is 1 Discus per 15 gallons if you wanna keep it comfy. But hey, if they're vibing and your water's on point, roll with it. Just stay sharp on those water changes.
Post Reply