A couple of weeks ago I bought 2 albino corydoras. I had them in the 400 ltr tank, but they seemed unhappy there - large, dark gravel substrate, and boisterous yo-yo loaches. So I moved them into the 160 ltr tank with white sand substrate, and more placid tankmates. They certainly seem to like it. My question now is - do anyone else's corys do this? Mine seem to LOVE doing this.