The intake of the filter tube should have at least a single layer grate over it. This is to prevent the bubble eye's eye from being sucked up against the end of the tube - essentially sealing the tube. The fish will be trapped - sucked against the tube until his eye collapses, or you release him. It can be a tramatic injury - life threatening.
Many ways of insureing intake saftey in a bubble eye's tank have been posted. My favorite is Koko's. She has the regular intake grate installed over the end of the tube, but has also fastened an empty plant basket over that. This creates an area between the intake grate and the plant basket grate. Even if the bubble eye's eyes are pressed against the basket, it still holds them off the suction - making sure there is no way a seal can be made, trapping the fish.
Bubble eyes tend to be a quieter fish than most - they do a lot of floating gently around and even hovering about an inch above the bottom of the tank. Because they like the bottom area so much, I would reccommend that you provide open space on the bottom of the tank for them - a place without rocks or plants or bubble bars or anything. This allows them to hover in peace.
My tank has a few roundleaved plants - soft ones, a very round river rock that is covered in soft thick green algae, and a bubble bar along the back of the tank. Mrs. Weebles is very happy to waggle around, showing off and watching me work.
I also have the output of the filter broken by a long piece of plastic that allows the return water to flow back in and then dispurse without creating a strong current.
Enjoy your bubble eye. I love Mrs. Weebles very much.