oh wow! I Love the shape!
honestly.... I think a saltwater setup would really suit that tank.
but otherwise, gets lots of colourful fish, with minimal decor to show off and accentuate the cool shape of the tank.
I think a combo of Angelfish, mollies, swordtails, corydoras would perfectly fit. They will add movement and colour.
I've seen some pretty cool TALL Setups. Here are some pics to give you ideas...
GOOD LUCK! that tank was a Great find