They just sit on top of the heater all day. They won't budge and I've only seen one of them eat. A little worried about them. There is 3 (I know they need schools of 6+, but didn't want to mess up water parameters by adding too many at once, 3 more are being added in a few weeks.) I thought cories were very active....is this normal for them to just sit there and not look for food or move around? The smallest one will sometimes swim a bit, but only for a little bit. Only tankmates are 1 dwarf gourami and 1 firemouth. I know the firemouth hasn't been bullying them, he's lived with cories before with no problem(he's moved from tank to tank until I got him this one). They were only added 2 days ago. They seem to swim a bit then get very tired and just sink. They never go to the bottom (expect for the smallest, he'll go down occasionally) Should I be concerned?