It's definitely a GT.
There's also a few different 'types' of Blue Acara, some will be more stocky with a slightly white tipped dorsal and a much more vivid black and white, and some will have a slightly red sheen in their fins and have a yellow or closer to orange line along the tips of their dorsal and about 1/3 of the way down their caudal fins.
I've kept both, it just depends on their location. What you've got there is most certainly a Aequidens sp. Gold Saum. Photos and descriptions can often be confusing and seem much alike, but after you've kept one or the other, you can quite easily tell the difference. Friend of mine has a 2-3" GT and it looks just like that.
