From the pictures you provided, they look great and right at home already. If you're calling that faint banding "the black marks on the sides", I wouldn't worry too much. From the pictures, nothing stands out to me as a potential issue. If you want specifics to keep a lookout for (to ease your mind when you don't see them

) -- you can look for a dusty - "fuzzy/velvety" appearance on the skin where the "marks" are, any change in eating, swim patterns, general behavior, spreading of any "marks/dots/etc", raised scales, excess slime coating, ulcers or tearing of fins...
I wouldn't worry about those marks, they might just be the fish's natural markings - perhaps not a 100% "purebred?" LOL. All in all, they look great, color is awesome, body proportions are right on par, eyes are clear, mouth and fins are flawless and they seem settled right in. But I agree with Kevin, better safe than sorry.