From the little research that i have done on this species of fish im leaning towards them being diphreutus......BUT, with that being said they were sold to me as black and white heniochus which is the common name for h. acuminatus. They dont have an extremely prominent mouth and have a rounded chest vs flat.....those seem to be the only distingusting factors. ID say come in and see if you can positively ID them and we can go from there. I will say that they do have an amazing appetite, but they do have a lil ick on their bodies. I have cleaner wrasses in there with them and im feeding LRS with some Garlic extract mixed in to see if i cant get em to kick the ick!