tell your fiance no that is not an appropriate home for that kind of fish....what your tanking about is a bala shark.... and most get over a foot and no way can a small 30 gallon tank handle a fish that get 12-14in....i bet that is wider then the tank is.......
if you do up grade to a proper tank 75+ gallons then yes you can have a few bala sharks and mollies will get along fine with them....
if you do up grade to a proper tank 75+ gallons then yes you can have a few bala sharks and mollies will get along fine with them....