Issue with live rock and previous owners "disappearing" clam

[Captain Quirk]

I have 3 croceas that are doing well in my current 90G tank.

I am setting up a 210, and have bought the rock from a friends tank.

At one point, he had a clam (also crocea) that just "disappeared" one night; he got up in the morning and it was just a shell.

This happened probably 6 months ago, and I put the rock in my new tank perhaps 2 weeks ago.

My question is basically whether or not I have to worry about putting my clams in this tank with his rock. He did not note anything wrong with the clam until it "died" (although I recall that its mantle would rarely extend, if ever. It wasn't mine so I'm foggy on details).

I'm worried that some parasite might be in there with the rock and will prey on my clams once I transfer them.

I was thinking I'd put them all in close proximity to each other and try to have "surprise inspections" during the night for a few weeks, to try to catch any potential poachers.

Any thoughts? Suggestions? Perhaps give them a lugols bath (or equivalent) every week or so after transferring them, in the hopes to catch/kill whatever may try to attach to my clams?

Thanks...

 

[skinz78]

If it were my rock I would treat it as if it just came from the ocean.

Basically mix up a bucket of saltwater with a very high salt content 1.030 -1.035. Dip the rocks in the water and let them sit for at least 5 min. Any hitchhikers that are in there should flea the rock trying to get to less salty water. If there is a hitchhiker this should scare him out.