I may not be as knowledgeable as some of the Canreefers on here, but I have a bit of experience with clams.

Clams close up if there is something that is bothering them. I am going to guess it is fish related, the strawberry basket cage is a good suggestion.

Having read your post about 0 Nitrates, that's a great thing for SPS, but not for clams. Clams consume Nitrates, so having a little is beneficial to them. I've had up to 11 clams at one point, yes I got hooked on them. I am down to 5 now, there is a delicate balance to keep clams and SPS.

SPS like "CLEAN" water, while clams like "DIRTY" water. I have found that to keep both SPS and clams, you have to keep the water parameters almost perfect for the SPS while dosing Phyto and or Sponge Power to feed the clams. I've got 2 Crocea's that I've had for about a year now, got them when they were about 3" and now they're about 5"

Another thing could also be your CUC, I lost a few of my clams due to them picking at some algae that was growing on the shells. It iritates the clams when hermits or even your cleaner wrasse is picking at it's shell.

I would suggest that you do 10% water changes weekly and see if it makes a difference also. Clams like everything else we keep in our tanks prefer stability, so make small changes gradually.

Your one of those people who have a dog and don't clean up. The yard aren't you??
Every person in this thread has tried to help you - well except me because it's obviously a waste of time but maybe just maybe take the advice of the majority of reefers here? Especially since many of them have much nicer tank(s) than you or me?
Don't ask for advice if you don't want it
And clean your god damn pets home

Could you please elabortate on "Crazy", if the water you are putting in is the same salinity Ca, Alk, Mg and temp you shouldn't run into any problems.

How are you drawing the connection between doing a water change and having aggression increase in your tank? I don't see a mechanism between the two, perhaps you can explain that to me.

It's your right to add 20 Morish idols to your tank if you want, you proved your fish wouldn't tolerate 1 so go ahead and lose 2 grand on being ignorant. The suggestions given here are for your tanks well being, take them as you want but don't flame others for anwsering your questions.

Thank you, you win for having the most helpful post.

Don't have a dog. And you're implying that my tank is dirty, which it's not.

My example was an exaggeration. I don't like being told what to do. I have the ability to research and draw my own ideas. And if someone doesn't agree I don't care.
I don't know what the connection is but after a wc the tang got territorial and aggressive.

Oh, FFS, it's pinched mantle. Give it a FW dip every other day for a week, it'll be fine. And change some water for the poor fish.

pinched mantle on both?

im sorry but i dont believe in coincidences.

but im gonna research it some more

either way, cleaner wrasse is out. literally swam right into the trap 5 seconds after putting it in, didnt even have a chance to put food in it yet

Yes, both. I don't believe people are still posting here, but look!!

oh, and freshwater is free, so no cost to try it. Take the time you don't use for water changes and dip the clams...