Gar Man. Sigh. I think you get the prize for Most Threads Started.
There's not a whole lot that's going to fit in a 5.5 g tank. A Betta or some same-sex guppies maybe. Smaller isn't better when trying to keep water parameters healthy. Just plant it 1st. Get your plants in there and let them grow for a few months...then add a Betta or a few female guppies.