Cory's sitting at the bottom of the tank

[Sapphe]

I've recently gotten back into fish, and an old issue I've always dealt with has resurfaced - from my 20 gal to my 40 gal breeder. The tank's been up and cycled for years, I just hadn't replaced fish until I was left with a lone cory. I'm currently running a 20 gal with 6 albino corys, 5 guppies, and a bamboo shrimp. I've got 2 Fluval 30 HOB filters, which is overkill, but I've got enough bio for a 40 gal, just in case I set it up again. Water parameters are all good.

The problem is, no matter what I try, my corys spend 95% of the time just sitting at the bottom of the right side of the tank. I've moved the tank, swapped filter positions, removed a filter, adjusted the filter speed, tried a canister (didn't like it), increased the bubbler, added stress relief stuff, done melafix and primafix, and treated for obscure diseases - nothing's worked. They'll move around to eat, but other than that, they're just not active. The guppies and shrimp don't bother them, either.

[tetraTim]

I've had corys before and they've always been pretty active, searching for food and sifting through the substrate. My current group of sterbai are quite lively too. I've got 9 of them in my tank, which has a sand bottom. How many corys do you have in your 20 gallon, and what kind of substrate are you using?

[Rampar]

I had a similar experience when I upgraded my corys to a bigger tank - they stuck to one spot for a bit until they felt at home. I've found they love chillin' under plants or decor, or even just hiding under overhanging rocks. Yeah, they'll sit still for a bit, but they're always on the move, digging through the substrate for food.

They're great at keeping the sand looking nice and sifted, too.

[Sapphe]

I've had corys before and they've always been pretty active, searching for food and sifting through the substrate. My current group of sterbai are quite lively too. I've got 9 of them in my tank, which has a sand bottom. How many corys do you have in your 20 gallon, and what kind of substrate are you using?

I've got 6 albino corys right now, and my tank's got a mix of sand and small soft rocks. Had the same issue when it was all sand, so I'm not sure that's the problem.

[Amiel]

I've had a pair of corys in the past, one was quite lively, always on the move, whereas the smaller one was a bit more laid back. It had been under the weather, so I added some salt to the tank to help it recover. I noticed it just sitting at the bottom, on the right-hand side, maybe it was just resting and getting back to full strength.

[floatie]

I've got 4 cories in my tank and they often do their own thing, sometimes all bunched up, other times spaced out. Feeding time's when they get active, swim around, grab a bite, then settle back in. Occasionally they'll surface for air, do a few laps, then head back to their favorite spots - and that's when they tend to bunch up again, usually in a shaded corner near a sword plant. Each of them seems to have its own preferred spot when they're not hanging out together.