They will only eat the external parasite and not cure the fish from the disease. Get some close up pics if you can and if it is in fact marine ich do a search, there's a million threads on the topic and a few different treatment options. Good luck!
Looks fuzzy white spot not ick not sure what that actually is called but a cleaner wrasse will eat it but my cleaner wrasse is a pest to few my fish so not sure he's worth adding as for the most part any serious illness they r not affective
Is it just on the tail? And how large are the spots, like a grain of salt, or larger? If they are a little bigger and sit just at the edge of the tail fin, it could be lymphocystis. Ich will make the fish flash (scrape and flick against rocks) and may make the gills move quicker (difficult to get enough oxygen when your gills are covered with parasites). Lymphocystis doesn't do this. It is a virus, and generally doesn't affect the fish much if it is sparse. If it looks this way, just make sure the fish is well fed and as stress-free as possible, and it will go away on its own.
It is lymphocycstis, I looked online at more pics. its exactly that. its white spots on its tails and top fins. What should I do to fix it. My hippo tang had it first then it went away after 2 weeks. now my yellow has it. Should I be concerned bc I have a unicorn tang in there as well. All tangs are roughly same size, juveniles (2-3inches).
Water btw is perfect 0 nitrates, ammonia 8.2 ph, salt .017-.020 I think, its low like the tanks in the stores to prevent infections.
Lymphocystis is a virus, and it's pretty much impossible for a hobbyist to get piscene antiviral medications. As long as you keep the fish in good condition otherwise (good water quality, feed them often with good quality varied foods) they should fight it off on their own.