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I've got a 55-gallon tank that's 12 inches tall. My Discus are about 4 inches now, but I'm worried they won't have enough vertical space as they grow. Anyone else run into this? Tank's got a Fluval 307, sand substrate, and a few Amazon swords. Water's at 84°F, pH 6.8, and I do 30% changes twice a week.

A 12-inch height is on the shorter side for adult Discus. They can reach 8 inches, and taller tanks (18+ inches) give them more comfort. Your water params sound solid, though. What's their behavior like? Any signs of stress, like hiding or rapid gill movement?

Yo, my crew's in a 75-gallon that's 16 inches tall, and they're chillin' fine. But 12 inches? Sketchy for big boys. You might see 'em cramping up. Try adding taller driftwood or plants to fake some height. Also, what's your feeding routine? Beef heart helps 'em bulk.

I agree with brites. Discus thrive in taller tanks because they're naturally vertical swimmers. Your setup sounds clean, but the height could limit them long-term. Have you considered upgrading to a 90-gallon? It's 24 inches tall and gives them room to stretch. Your current plants and filter would transfer easily.

Nah, 12 inches ain't gonna cut it, fam. My Discus started acting weird in a shallow tank, like they were bumping into each other. Upgraded to 20 inches, and now they're golden. You running CO2? That could help your swords grow taller and give 'em cover.

brites wrote: ↑Mon Aug 11, 2025 5:39 pm A 12-inch height is on the shorter side for adult Discus. They can reach 8 inches, and taller tanks (18+ inches) give them more comfort. Your water params sound solid, though. What's their behavior like? Any signs of stress, like hiding or rapid gill movement?

They're mostly calm, but one darts to the top sometimes. No rapid gills, though. Thanks for the input, everyone.

That darting could be a sign they're testing their space. If you're not ready to upgrade, try lowering the water level by an inch or two. It's a temporary fix, but it might reduce the 'ceiling effect' until you can get a taller tank.

vital wrote: ↑Mon Aug 11, 2025 10:09 pm Nah, 12 inches ain't gonna cut it, fam. My Discus started acting weird in a shallow tank, like they were bumping into each other. Upgraded to 20 inches, and now they're golden. You running CO2? That could help your swords grow taller and give 'em cover.

For real, CO2's a game-changer. My plants exploded, and the fish love weaving through 'em. What's your lighting schedule, basis? More light + CO2 = taller green cover.

If you're considering CO2, start slow. Too much can swing your pH and stress the fish. I run mine at 20 ppm with a 6-hour photoperiod. Also, what's your tank's footprint? A 55-gallon is usually 48x13 inches, so they've got horizontal space at least.

Yeah, CO2's dope but don't go wild. I messed up once and nuked my tank. Now I use a drop checker and keep it steady. Basis, you got any tankmates in there? Tetras or corys? They can help the Discus feel safer, even in a shallow setup.