The stripe edges looks more "serrated" than in the other pics, so I'm going with SAE. LFS often call them flying fox SAEs just to cover all the bases. True "foxes" , like Joel said, have a definite gold stripe above the very solid smooth black line. There are several very similar species to SAE, have a look at the SAE post at the top of this page for some more confusion, lol.
Yours is of the social kind but 1 is ok on it's own, just 2 may fight a bit...but usually just over food, nothing serious, they are piglets...but active & attractive & much prefer fish food to algae IME unless very hungry. Mine ate constantly, grazed algae but never really got rid of it all, just kinda kept it in check for the most part in a 75g 4ft tank