My experience is that these fish are very sensitive at first, but once they're fully acclimatised, they are quite hardy. I lost most of a group to suspected columnaris last year, and when I introduced another group a couple of months later, lost most of them too. I had high hopes for the new group, couldn't believe my bad luck...
Are these fish flashing? Some of mine were, and some developed the same tiny red dots. I suspected bite marks first, but since there was flashing too, I thought of skin parasites (flukes, trichodina?). Never found it out though. Maybe there were many things going on, and the red marks just one of them. I don't think I did too well in trying to medicate them. Since starting with Fluke Solve there were no losses, could have been a coincidence too. Anyway, the ones I have left are doing very well.
As far as I can see in the pictures, these fish look otherwise good, round bellies and clear fins. Keep an eye on them and offer them loads of fresh water, hopefully that's all it's needed.