I have air stones or curtains in most of my tanks. The catfish and gouramis really like swimming in the bubble streams and it helps the oxygen levels.
I never see my leucomelas cories. I will see one occassionally. I often wonder it they are still their. When I first put them in the 100 usg they were out to play all the time, lined up at the glass to be studied. Now I worry about them all the time and wonder if they are still there. The peppers come out without hesitating but they don't play much. I have so many bottom feeders, they have to work for their dindin. But the leucomelas are really shy.