Keith,
It looks like your fish either picked up an infection or came with one. Bacterial,viral or parasite is hard to tell but the time frame probably indicates protozoans.
It sounds like you didnt quarantine these fish, just added them to the 125?
Thats going to make treatment harder with the substrate. I think a good action plan would be to try seachems paraguard or formalin+malachite green. You will also want to increase your water changes to 80+% a day.
This all goes under the assumption its parasites.
The alternative is to assume its bacterial. If so, Then 10days of furan 2 is worth trying instead of the other meds. The problem is symptoms for the two look similar.
I would definitely get in touch with your hatchery. The fish either came with the problem or picked it up in your tank. The seller may have more suggestions or insight.
I cant stress enough why its so important to quarantine new fish.. What you have going on here illustrates it . 6 weeks is a good quarantine period.
hth,
al