Well, some fish do have small tips or spots on their fins. Make sure to look closely, and see if the white dots (ich parasites) are elsewhere on the fish. If so, it's probably ich. But, the good news is that if the spots are that invisible, you don't have a bad case of the parasite. Your fish should be fine if you follow the advice.
Nota Bene: ich medicined kills the free-swimming, just-hatched, (pretty much invisible) parasite, not the matured, white-spot, parasite you see on a fish. Make sure to do the appropriate water changes to get rid of it. The instructions should guide you to do this correctly.