Coral Beauty with Clam? Been in Tank 6 Months and hasn't Messed with Anything!

[Highest20]

So I have a Coral Beauty that is a Survivor...All My Fish Died from Brook and the Angel Survived. Hasn't touched any Coral. I have Acros, LPS, Acans, Mushrooms, Zooanthids, Etc. I Know Potentially Dangerous to add a Maxima Clam. LFS has a Cool Maxima about 2" for $90. Guys there Said Introducing a Clam Might Cause the Beauty to Eat the Clam and then Cause appetite for Other Corals that hasn't touched B4. Im ok with losing the Clam but Definately don't want it going crazy and killing everything else! Also the Tank is a 20 gallon Long So Kinda Small maybe makes a difference...Any Help and Advise is MUCH Appreciated! I REALLY Want this Clam but I don't want to Lose $90 especially More. Peace.

 

[Roatan Reef]

My Coral Beauty is a Model Citizen, never touches corals, isn't mean to anyone, only when another fish tries to get in his cave spot, but even then, it's a light nudge to tell them to move.

 

[littlefoxx]

I have two angels, a regal and a french. I feed them clams on a half shell and they devour them! Even got the tangs eating them. I had a clam in my other tank with w golden dwarf, he ate it one day. Based on the angels I have I would say clams are a desired food for angels once they get a taste of one!