You asked for my input, so I will give it, even though it counters some of what has been suggested.
I would never use copper in a fish tank, at least not for ich or similar. Salt is considerably safer for fish like cories, loaches and characins.
As for treatment, I myself would likely sit this out. But you are there to observe the fish and are the better judge. Are they flashing? I have known a "spot" appear on a fish and then disappear with no obvious follow-up. Jumping into treatments is not usually the wisest decision. Clean water and avoiding stress can work wonders.
I know some do not agree, but it is now held that ich can live in an aquarium for some time without any spots ever appearing. A flash once in a while is generally the only indication, because ich first attacks fish in the gills, and just one parasite getting through the treatment is all it takes. If the fish encounter some stressful situation which weakens their immune system, this can cause the infestation to take off. In nature they develop what some may term an immunity, but it is certainly a resistance. No one dumps copper or salt in the natural water, but fish are still there so the ich obviously does not decimate them. Nature can best deal with nature if we provide an environment suited and free of stress.