SAE identification

Yesterday I picked up three 3 to 4 CM fish labeled algae-eating sharks
at the local pet shop. In every respect but one they seem to exhibit
all of the signs of being the true SAE: reticulated back, pointed snout,
mouth on the underside, no coloration on the fins or anywhere, as
well as the streamlined shape. They eat algae. There is one difference.
The black body line extends only slightly into the caudal fin. Is this
a characteristic of juveniles of the species, or might this be another
related species? They are unlike the false SAE, nor are they flying
foxes since they lack the coloration.

Message to all living in the Ottawa-Montreal corridor: Whether or not
these turn out to be SAEs, would any of you locals be interested in
getting together to order a shipment from Florida sometime after 
Christmas? I need about 18 myself. Or I could have the shop order a
few more. E-mail me if so.

By the way, the botia lohachata ceased their obnoxious behavior after
eating three Amazon Sword leaves. They seem to prefer cooked zucchini.