Basic questions for a derasa clam

[Onixom]

So awile ago i bought a stoney coral and its been thriving so after visiting my LFS recently and saw they had this beautiful clam (they dont normally stock it but a new lad has taken over the coral side of the shop)
Its only 2inches in size (lads we can agree thats quite large) so in my head i thought of the basic stuff like wave my hand over the top of the tank and it retracted immediately and that if im supporting a stoney coral it should survive.

So i've got it home and acclimated it to my tank water and drip acclimatised to the parameters and checked for any hitchhikers and placed it in a nice little spot on the rock work within an hour or 2 it had opened up and was happy as larry (From what i can tell)

So my main question is obviously how fast will they move to find a spot they are truly happy like do they move within 5 mins of placing or does it take a few hours before they choose to find a better placement.
If they do move do i just leave them till they are positioned or will they require help
Will they be alright to sit on sand or will bristleworms eat them.

(From what i can tell its a derasa clam)

 

[flashsmith]

In my experience Derasa prefer to be on the sand bed and don't require intense light like maxima clams. At that size I would recommend feeding the tank phyto if you don't already. Once they hit a certain size around 3-4 inches you will no longer need to do that.

 

[Onixom]

In my experience Derasa prefer to be on the sand bed and don't require intense light like maxima clams. At that size I would recommend feeding the tank phyto if you don't already. Once they hit a certain size around 3-4 inches you will no longer need to do that.

I've bought some phyto today after reading about the smaller ones needing additional food so have dosed a little into tank

 

[Mr. Mojo Rising]

they don't "move", they can wiggle slightly and move a few millimeters, but it can't climb rocks or get from one end of the tank to the other. They need to be placed in the proper spot.

wether on sand or rocks, it needs strong light. Feeding not neccessary, just strong light. Bristleworms won't bother a healthy clam.

@OrionN @Spare time can help identify and offer more info

 

[flashsmith]

Mine moves every day. Wiggles around to where he likes the flow over his mantle. He has about a 10x10 area on the sand bed he moves around in. Usually by the end of day he's pretty much on his side and then in the morning he's upright again.

 

[Onixom]

they don't "move", they can wiggle slightly and move a few millimeters, but it can't climb rocks or get from one end of the tank to the other. They need to be placed in the proper spot.

wether on sand or rocks, it needs strong light. Feeding not neccessary, just strong light. Bristleworms won't bother a healthy clam.

@OrionN @Spare time can help identify and offer more info

Here are 2 better photos (not sure if they help?)

 

[OrionN]

“a while ago…” is how long? You do have a Derasa. If it have been in your tank for several weeks it should have some growth, white shell at the edge. You need to worry if it does not growth.
I necer feed my clams. Just nutrient from the tank, good water and light.

 

[bushdoc]

I have humongous Deresa Clam ( her name is Theresa), which has been with me for 8 years or so. It lost byssal gland like most of them and since I have bare bottom tank, I positioned my clam on the rock.
I constructed some sort of secure platform, so it cannot fall from it. If you have sand, you might prefer to put her there. Deresa cannot move freely , but it can sort of "wiggle', by rapidly closing and opening shells, so it is important to position clam either in a sand or if on the rock, it should be prevented from falling.

 

[Onixom]

“a while ago…” is how long? You do have a Derasa. If it have been in your tank for several weeks it should have some growth, white shell at the edge. You need to worry if it does not growth.
I necer feed my clams. Just nutrient from the tank, good water and light.

The stoney ive had around 2.5 months and its not died so that led me to buy the clam yesterday.
I should have put more thought into it however as i stated it was the first one the LFS has stocked since i started going there

 

[Mr. Mojo Rising]

I can see the white line of growth at the top of your clam shell, it looks healthy and happy to me. Always keep an eye on that white line, it will tell you if the clam is growing. But so far so good

 

[Onixom]

So i have moved it to the sand below and its twisted itself to face the light but not moved otherwise and it looks to be even happier (Hopefully it is and im not mistaking something bad for good?)
The power head is not directly on it but its pointed in the general direction and clashes with another creating random currants

 

[minus9]

Feed your fish food and feed the clam light, lots of light. At this size you should see a pretty healthy growth rim at the top of the shell. T. derasa have a pretty good growth rate (about 1" - 2" per year) when provided the right amount of light. I don't see a lot of growth here, so I would up your lighting some more. I would also buy James Fatherree's new book on clams (it's $36 all day long on Amazon), which should help you understand their biology/care better.
As mentioned earlier, bristleworms will never attack or eat healthy living tissue. They are one of the best free CUC you can have in a tank, their numbers have a direct correlation with available food.

 

[Netotek]

How large will one of these get? yours looks gorgeous btw

 

[OrionN]

I got this Derasa no more than 3 months ago. Grew quite a bit. It is around 3 inches now.
they can easily get to 12 inches in 4-5 years. My clam likely under a lot more light than @Onixom

 

[minus9]

How large will one of these get? yours looks gorgeous btw

T. derasa is the second largest species out there, so they will grow pretty big in our tanks. Expect 15" to 20" with 18" being the average size. I've seen a cultured derasa that was at least 20" and it took up a lot of room in a 150.

 

[OrionN]

I went back and look. I got mine from Petco 2/15/2023. It was weeks before he star to grow since he was in poor shape at Petco.looking at the shell you can clearly see a gouge divided the growth in my tank from before.