Please help with Dersea problem

[Wrench]

I just got a new Dersea yesterday. Placed it in the tank and some Nassarius snails immediately converged on it's mantle. They only attack dead tissue so I had a closer look. The mantle on one end of the clam, opposite of the byssal opening, does not extend when the clam is open. With a closer look I noticed some dead tissue on the edges of this area of the mantle. I don't see any snails, worms or other pests. I am not familiar with what pinched mantle looks like but from the images I've seen, this is different. I have two questions.

1.) Will the nassarius cause further damage or will the help?
2.) What should be my course of action as far as getting this guy healthy, FW dip?

[mbbuna]

FWD's are not a cure all. in most cases they do more harm then good.

if the snails are attacking it they will kill it not help it. i would remove the snails. there are whelks that look just like nassarius snails and a lot of time they are sold as reef safe nassarius snails

[a4twenty]

this may help you tell the difference click me

[Wrench]

According to the info on that site I definitely have Nassarius. Very fast, no markings on the snout, they move FAST and never climb the glass or rocks. They only go after the dead tissue on the one side of the clam.

Update on the clam, today it's closed up tight.

[a4twenty]

Originally posted by Wrench
Update on the clam, today it's closed up tight.

what fish do you have?

[Wrench]

Clam is dead today All of my other clams are doing fine. This is a new addition and I noticed problems as soon as I put it in. I'm thinking there was something wrong with it when I got it.

Fish are;
Powder blue tang
Yellow tang
Tomini tang
Lyretail anthias
Green chromis
Cleaner wrasse
Clown fairy wrasse
Diamond goby
Ocellaris clowns
Pink tail trigger (added since the problem started)