New Crocea Clams - Some opening some not?

[hilde123]

I purchased 5 crocea clams (very small) about 3/4-1" to add to my tank. I added these about 1 month ago. I've had two Deresa clams in the tank for about 4 months (they have been doing great). I have had several clams in the back and done well keeping them alive for many years. My question is some of the new clams are opening as normal and seem very happy but some are not and are staying mostly closed during the day. It seems that they open up more in the morning when light intensity is lower and in the evening when similarly light is less intense. However, the clams that are doing good and bad are at the same tank depth so getting similar lighting. Below is some pics and tank chemistry. PAR is about 300 where they are located in tank. Any ideas of what I should do or is it common for it to take several weeks to a few months for certain clams to get comfortable in their space?

Temp 77-78
PH - 7.9-8.1
SG - 35 ppt
Alk - 8.9
Calcium - 460
Mag - 1350
Phosphate - .006 ppm

 

[JohnL]

Have the unhappy ones ever seemed happy?

 

[kfisc]

They open more to grab more light as needed? My experience with croceas was that they could stay shut for extended periods when moved or newly introduced relative to other species. Also, the smaller, the riskier. Good luck!

 

[hilde123]

The unhappy ones did seem to open more a few days after being put in tank. Today the unhappy ones seem to be opening a bit more, still not fully though, maybe 50% open. I'll see how they do over the next few days.