Anthias are known for sudden death in fish tanks. I assume he also came from a LFS? Any idea how long they had the fish in their tank and did you ask them to feed it (so you could see whether it was actively eating) prior to purchase?
Both of the clowns should have been vibrant, different salinity levels or not. Did you acclimate any of these fish to your tank?
Just a heads up..fish need to be:
A- QT'd before adding them to your tank
B- acclimated properly to the salinity & temp of your tank
C- added slowly or your bioload cannot keep up with the additions and your ammonia level will go off the charts
Have you tested your water parameters? All of them? (Ammonia, Nitrate, nitrite, Ca, Alk, Mg....) What is your temp & salinity?
Not to be harsh but with no skimmer on this tank and only 40 pounds of live rock in there, you are heading for a total wipeout of your fish as you don't have much of a bio-filter going on. The load needs to be reduced asap so this doesn't happen.
How long has this tank been set up? Was it properly cycled?
I would
not treat for Brooklynella at this point as you may well not have it. Just because the fish looks white-ish after death, doesn't signify Brooklynella. You may possibly be dealing with ich, but until you see clear symptoms of it, I would not treat at all.
I still believe you need to do a major water change (test your parameters before & after!) in the neighborhood of 50%.
IMO, I'd return or sell the 2 tangs to start, they product copius amounts of poop that your system cannot handle. The Koran Angel is also way too large a fish for your tank and should be re-homed too.
http://www.peteducation.com/article.cfm?cls=16&cat=1879&articleid=2008
What kind of wrasse do you have?
It's always best to research fish before you purchase them to be sure that you can provide the proper environment for them to be able to thrive. Many of the fish you have purchased are inappropriate for the size tank you have. Is the LFS giving you this advice?