Trichopsis pumila; 1.5", personally i think you'd be better off with 5 sparklers as they are (apparently) very sociable fish.
If that is you believe an 8 gal is big enough for any Gourami.
Please bear in mind if your looking for a small cory that stays on the bottom, then better of chooseing habrosus as pygmaeus is a mid water swimmer.
Just a small point as I once made this wrong choice.