Derasa on rockwork ok?

[SamMule]

I got this derasa a couple of days ago. Was a deal I couldn't pass up. I can place it in the sand bed, but the lighting is so much better on top of my rockwork. Really brings out the colors. Whereas in the bottom, it's a bit washed out. It seems happy and opens fully.
Will a derasa attach via byssal threads to rock just like a maxima? Or does it need to be in the sand?

 

[OrionN]

It forms very weak byssal attachment that won't hold the clam in place. As long as it is stable and won't fall over, it will be fine. There are three areas on the mantle that seem irritated. Keep an eye on it. May be symptom of PMD, or something took a bite out of the mantle.

 

[SamMule]

Yes, I see that. One of my wrasses may have taken a bite. The Christmas Wrasse has been swimming by and eyeing it. I will be keeping an eye on it for sure

 

[OrionN]

Way-back, umpteen years ago, I had a H. chrysus turn rouge and start to take chunks out of my clam mantle. I have to removed him quickly.

 

[Mr. Mojo Rising]

thats a nice looking clam!

 

[JoJosReef]

It forms very weak byssal attachment that won't hold the clam in place. As long as it is stable and won't fall over, it will be fine. There are three areas on the mantle that seem irritated. Keep an eye on it. May be symptom of PMD, or something took a bite out of the mantle.

Do they actually prefer the sandy substrate or is it more of an attachment issue for them, i.e. rocks usually too much flow that knocks them over?

I'd love a derasa, but like OP, it would get better light at the top of my rocks. I've even thought of making a type of sand-filled cradle on top of the rocks if that's what would make it most comfy.

 

[i cant think]

I got this derasa a couple of days ago. Was a deal I couldn't pass up. I can place it in the sand bed, but the lighting is so much better on top of my rockwork. Really brings out the colors. Whereas in the bottom, it's a bit washed out. It seems happy and opens fully.
Will a derasa attach via byssal threads to rock just like a maxima? Or does it need to be in the sand?

If you have an area on the sand that’s open you may not have that issue - Deresa can go down into the 200 range in terms of PAR. Mines still rather young (only about 3 inches long) but this is where I have mine. It’s not too close to the rock and slightly out in the open so I get the colour from it.

 

[minus9]

As @OrionN mentioned, if there's a safe place where it won't tip over in the rock work, it should be fine. But long term, I would look for a place in the sand that you can provide strong lighting and move it there. The three larger species that we keep don't stay attached for long, they depend on their weight to keep them in place and in some species the byssal opening fusses shut completely. Derasa being the second largest tridacna, will lose it's byssal attachment soon. Beautiful clam, and yes keep an eye on that wrasse.

 

[SamMule]

Thanks for the advice. I did end up placing it in the sand bed during my water change yesterday. It hasn't opened back up all of the way yet. However, it is in a pretty high traffic area and closes up every time a fish swims by it. Hopefully it will adapt and settle in down there. Haven't had a chance to observe today, as I'm at work, but I have my fingers crossed.

 

[SamMule]

Figured I would update this thread. After a few days in the sand, the clam did not look good. Ended up with a hole in the mantle. So, I moved it back up on the rocks where it was and it has recovered nicely. All nip marks are healed and it is growing rapidly!