Distichodus of some sort, as said above.
Lovely looking fish, but in an appropriate sized massive aquarium (think 10-foot long or more), some species can reach over 60cm. They are also very aggressive with conspecifics, a group of four ~12cm juveniles at my favourite LFS got very nasty with each other a month ago, at least one came close to death.
Edit: Have you bought it, or is that photo with foreground plants from the fish store? If so, besides the tank size requirements and the conspecific aggression, you need to know now that real plants are going to be attacked by this beauty
http
/www.seriouslyfish.com/profile.php?genus=Distichodus&species=sexfasciatus&id=200 (lusosso and affinis profiles are there too, but site seems to be down at mo, great for fish profiles)