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FAQs about Behavior of Giant Clams, family Tridacnidae

Related Articles: Got Tridacna? A beginner's guide to keeping Tridacnid clams by Laurie Smith, Example Chapter from NMA Reef Invertebrates book, on Giant Clams, Tridacnids, A Brief Guide to the Selection and Placement of Tridacnid Clams by Barry Neigut, Tridacnid Health: Pinched Mantle Syndrome in Giant Clams by Dr. David Basti, Deborah Bouchard & Barry Neigut, Bivalves, Mollusks, Lighting Marine Invertebrates

Related FAQs: Tridacnids 1, Tridacnids 2, Tridacnids 3, Tridacnids 4, Tridacnid Clam BusinessTridacnid Identification, Tridacnid Behavior, Tridacnid Selection, Tridacnid Compatibility, Tridacnid Systems, Tridacnid Lighting, Tridacnid Placement, Tridacnid Feeding, Tridacnid Disease, Tridacnid Reproduction, Bivalves, Bivalves 2, Lighting Marine Invertebrates,

I hope I did not speak too soon! Maxima Clam beh., Clownfish comp.  - 8/28/12
Hi Bob,
In my previous email I mentioned that my blue maxima clam and his BTA friend were thriving in my aquarium.  My clam has since left me with a question.  I hope I did not speak too soon.  He was approximately two inches when I purchased him about 8 months ago.  He has grown about a quarter of an inch since then, maybe more, but I am sure less than a half of an inch. 
<This family, species does grow slowly when small>
  At the time I purchased him, I placed him inside a skeletonized half shell of a much bigger clam that I purchased with some live rock.  I placed some substrate inside the empty half shell and placed the little maxima clam on top.  Within 24 hours he secured himself to the shell and as far as I know has been happy as a clam ever since.
Well last night he jumped shell.  I found him this morning open and beautiful, sitting in the substrate next to his old home.  My first thought was, well maybe he was outgrowing his home.  My concern came when I looked at the empty clamshell that he previously lived in.  I thought I saw the head of a feather duster worm, but upon closer inspection it resembled a white muscle with a bunch of filaments sticking out of it, and it was attached to the empty clamshell.
Well time to panic, right?  Could this be his byssal filament? 
Can clams leave part of it behind if they decide to move?
<Mmm, not usually>
 If this is a serious problem, how long before he deteriorates, because he still looks very colorful, is responsive opening and closing properly if i wave my hand above him.  He placed himself straight up, not on his side or anything like that.  He has not reattached himself to anything yet, so i placed a large flat rock underneath him and the substrate, because I really do not want him to attach himself to the glass, I like to know that in an emergency I can relocate him if necessary without injuring him.
Perhaps what I saw attached to the empty clamshell was not even part of my precious maxima.  That is the best I am hoping for.  OK I just lied to you, the best I am hoping for is for you to tell me that this is some form of asexual reproduction
and soon I will have a another baby clam on my hands, but since I have never run across that in any of my reading on clam care, I will chalk that up to fantasy.
My major concern is that assuming the worst and he did leave part of his byssal filament behind, is this normal?  Can he survive it?  What are the signs of deterioration?
<Mmm, loss of responsiveness, colour...>
I have a sand sifting star, indigo dotty back, cleaner wrasse and four clownfish.  The clam is more than 6 inches away from the BTA.  Nothing that I can think of that would be picking on the maxima clam.  He is placed in the bottom of the tank where he is catching the spread between a 10k led over the center of my tank and a 65k led on the left side of my tank. As always, any advice would be greatly appreciated.  Incidentally Bob, if I do decide to remove a pair of my clownfish to mate, perhaps causing the next dominant male to become female, would I ever be able to add the clownfish back into my display tank or would having two females cause a blood bath? 
<If there's room, not usually a problem>
Thank you as always,
Christine K.
<Be of good cheer, Bob Fenner>
Re: I hope I did not speak too soon!     8/29/12

Bob thank you for your quick response.  Just one more question if you don't mind.  If the clam is damaged in some way and will not survive, how long of a deterioration process should I expect?
<Likely a few days>
 In other words, when can I stop holding my breath? 
<The same period>
It has been 24 hours and he looks/acts fine.  If he makes it 48 hours, can I start to think he may survive?
  Or is it more like weeks or months?  I feel very confident that if he secures himself to his new home within the next few days then I may be out of hot water, but barring that scenario, if he continues to look/act good, when can I start thinking we may have made it over the hump, and besides watching him, is there anything  else I can do?
<A boost (one time) in iodide-ate dosing is prudent. BobF>

Coral identification & gigas clam shell formation question 9/23/08
WetWeb Staff,
First I just wanted to say thank you for providing such a wonderful service.
I just have two quick questions. First, regarding Dendrophyllia, I purchased a few heads from two different online vendors and can only positively identify one colony as Dendrophyllia. I suspect that the second colony might be Tubastrea, but I am really not sure. I was hoping that you wouldn't mind taking a look at the picture attached and offer your best guess as to what the second colony is. I know that the only true way to determine the species is to examine the skeleton, but your best guess would be greatly appreciated.
<The photo sent appear to be of the genus Dendrophyllia>
My second question is concerning the growth of my gigas clam. Once again, this was an animal acquired from an online vendor. I have had it for just about 3 months now and it is doing fine. I have noticed about a half inch
of new growth, but what concerns me is the unusual shape of the shell. I'm guessing that since the clam is doing so well, I really don't need to worry about it, but I am curious to know if the growth pattern has a chance of
harming the clam as it grows larger. Pictures are attached for your review.
<Not to worry... growth will slow, the shell change a bit going forward>
Thanks in advance for your response, and thanks once again for providing invaluable service.
<Again, welcome. Bob Fenner>

Jumpy Clam 9/12/08
I hope you can help me with a jumpy clam. It is a 2" Crocea. I got it about a month ago. I have 2 other Croceas that I have had over a year that have grown at least 2" each. I put the new one in about the same lighting situation the others are in. I have a 250 MH light & lots of rock.
All water tests perfect except nitrates just at .05.
My problem is that he starts to put his foot down & the light goes on or off, a fish swims by or maybe I feed the fish & he jerks & pulls the foot back in. About 95 % of the time he does this so hard that he shoots right off the rock. Finally today I put him in a small clear glass ramekin with sand and a small flat piece of coral imbedded about 1/2 way down in the sand. My question is this how long can he stay that way?
<A while considering all else is well.>
I tried to put the small piece of coral rock right under him but he kept falling over into the sand, mantle down. I am at a loss as what to do for this guy. I could see it if he wasn't happy with where he was placed, but this jumping/flinching, I just don't see a way to get around that.
What do you suggest??
<For the time being I would place him in the sand with the small rock or even a shell beneath the clam. This will give it something to attach to and a stable place to acclimate without jumping or falling off. After a few weeks with all being fine, you can then place it higher up, a bit at a time.>
So far he is still opening quickly after being moved and his mantle opens quite far but I don't think that too much more of this will be good.
<No, the constant moving and related stress will take its toll.>
Thanks for any help or suggestions you might have
Tina Taylor
<Welcome, Scott V.>

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