I was given a 3,5 gal with a beautiful, lazy lazy betta two months ago. Yesterday I was deep cleaning the tank because some new gravel I added had turned my water pink. I changed some stuff around to keep the lil guy entertained. The tank I have has some sort of platform that holds the air tube seen in the picture. I failed to properly cover a corner and in less than 12 hrs he's gotten stuck in the tube three times. I'm worried because twice he's gotten in there and in a matter of seconds stops moving and sinks and just curls up on the bottom. Could he be stressed and looking for places to hide? I have a couple of fake plants and rocks inside,but no formations. Or is he sick or trying to let himself die? I have no previous fish keeping experience and only go by what I've read in forums.