It is never a good idea to add a fish with the idea that you are going to move up in the future. Things change, marriage, divorce, unemployment, a move etc.

If you have a gold rim tang A. nigricans (it does not have orange on it like the powder brown tang A. japonica, remove it and take it back to the lfs. They should not be available for sale. For some reason this specie of tangs are almost impossible to keep (often refusing to eat).

Your tangs are algae eaters. Do as has been suggested.
Do not feed macro algae until the fish are treated.
Feed only garllic extreme or garlic extract soaked food as the idea is to get as much in the fish as possible. Feed very often. Dry food like spirulina disks or pellets and nori is best as more garlic is absorbed.

In the future only stock one fish at a time one month apart. It avoids many water, cyno and algae issues.

Well a lot happened today, my sailfin died. I saw that coming tho and it turns out that its not a gold rim as i was told by the lfs its actually a naso tang. I noticed this when i was browsing another lfs while i was waiting for food and they had it labeled correctly then i did some more research and it was a naso not a goldrim. Also i got some of the plant from the lfs and my naso is eating it and looking really good. Only has like 1 spot on its fin other than that completely clear. I know im a moron for not even really knowing what fish i was buying but o well. Im happy with my fish now and in the future ill do a lot more research before i buy a fish, and not introduce 2 fish at a time. Thanks for all the help guys, if anyone has any hints or anything on naso tangs it would be appreciated.

Thanks
tony

Naso's get huge....

And they grow quickly so get the tank upgrade in overdrive.

Naso's are iffy tangs to keep. They like lots of surge so if you do not have it place a powerhead near the surface of the water.

They eat brown algae so make sure some brown algae is part of there diet.

I suggest as a preventative measure you do the garlic extreme feeding regime as you know that there is ich in your tank.

i still cannot get him to eat anything other than the plant from lfs, he does eat all day tho grazing on some algae but will not eat anything i put in the tank. so ill have to get something else but i really dont know what ill try. Also i am soaking everything in garlic, even the nori i try.

Have you tried brown algae?

no, how would i go about getting some?

I forget he name "something select". Try the brown alage which come in sheets or tears and wean her onto nori which is far cheaper. Also try the brown algae with garlic extreme which can act as an appetite enhancer.