How is clam size determined?


Premium Member
Hello, I've just become the proud (first time) parent of 3 Crocea clams 2 nights ago and this is my first post to this forum. I just bought Daniel Knopp's book last night, but haven't had time yet to digest it all. I'm also reading all the back posts here as fast as I can and haven't seen an answer to this yet. I see that how much you need to feed seems largely dependant upon the size of the clam. When people refer to the size is that the size of the just the length of the shell, or does that include the width of the mantle when it is open? While I'm asking, is it common for it to take a day or two before the clam opens its mantle fully. Mine are in a 180 gallon w/ 2 400w 10k MH (soon to have a 3rd) and 2 140w VHO lights. For now at least the one not yet attached is on the sand (I will try to find a small rock for it today) and the other two are on ~3" high rocks, on the sand. Thanks in advance for your help!
Just the length of the shell. How wide the mantle is doesn't seem to be all that important. It can take a few days to acclimate especially if the tank it came from had less lighting than your tank which is more than likely the case....

Thanks for the help Cameron! I'm anxious to get home and see how my new kids are acclimating today! :)
Well you said you have had them a few days already so I guess it doesn't make that much difference now. I hope that you acclimated them to your 400watters as that is a lot of light for them to start with unless they were under 400watters when you go the but then you should have acclimated them slowly regardless. Starting them on the bottom and over a few weeks raise them to where they will be.

T. Crocea are a little more senitive than T. Maxima or T. Derasa as their gills can get clogged easier so try not to stir you sand up to much.

Glad you got Daniel book, good reading.

Shot us some picture if you can.

Yes, I have one directly on the bottom, since it isn't attached yet and the other two as close as I can get (they are already on 3" rocks) to the bottom. If they do well there, I'd like to keep them low. I never saw them in their original tank (sold through a friend) but they are Reef Central folks and my gut tells me they were well cared for. I should be able to find out what the lighting was - forgot to ask. I haven't mastered the art of taking a decent tank picture yet, but I'm working on it. Thanks for the advice Toptank! I already dose w/ DTs 2x/week and will be stepping that up to every other day I think.
toptank said:
T. Crocea are a little more senitive than T. Maxima or T. Derasa as their gills can get clogged easier so try not to stir you sand up to much.


After re-reading this, I can see I may have a problem with the one directly on the bottom. I've got a very active sand stirrer - the Orange Spotted Sleeper Goby (the one my husband calls the "Shovel". He hasn't been too big a nuisance up until now and he's so darn cute I'd hate to give him up if I can help it. I'll probably need to try to get the unattached clam onto a 2 or 3" rock of its own to keep the sand off. If some sand lands on it in the meantime, can the clam "expel" it? I watched a hermit crawl on it last night and the clam gave a nice powerful spit and off the hermit flew! I gave the clam a nice ATTABOY!
Just be careful. I gave 2 crocea on my substrate at the present but am just careful.

Only passing on what Daniel Knop told me when we were taking about how different T. Corcea where to keep as compared to T. Maxima.

IMO I think that T. Crocea are really beautiful. Here is my 6"

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Thanks for sharing - beautiful clam! One of mine is a deep purple/blue with reddish speckles; one is what I guess is referred to as gold with purple and some other colors in it. The other is also gold, but hasn't opened as fully yet, so I don't know how colorful it is. The two gold's are definitely Crocea, but I'm starting to wonder if the blue is really a maxima. The shell is much smoother than the other two. Maybe I'll be able to tell after I read the giant clam book. I will take pictures and post when I can. Thanks!