Yeah I would be pretty darn certain you have a female!
So find a male, either white or gold strip, small as you can, about an inch and a quarter or less.
Place it in any sort of floating container or breeder box (petco sells them for like $5)
Let the new guy float, maybe a day, two or even three days, watch female.
She should be curiously checking him out, and not frantically trying to lash out at him.
A female may reject a male for no apparent reason, and could easily kill him before you can even grab a net, so this is the best way.
Here's pics of mine.
You can tell even just in pics she is cool, otherwise I would have got blurred shots and cheek spines flared!
She should be curious, not furious.