no offense I have definately see more rays pass through my tanks fresh from the wild than 99 percent of ray keepers....I have seen many a ray break down after import and recognize the signs....If you dont see parasites dont treat for em unless the ray is wasting away....all fish have a parasite load and healthy fish can live a perfectly healthy life with them.
Im thinking your ray is suffering from its recent shipping across the country as well as a recent import with no acclimation time in between..I have had alot of success treating these haze problems with Binox but I would hesistate to reccomend anything to you without seeing the rays in person etc... first thing u need is water parameter check.... also some salt wouldnt hurt