Does growing mean he is happy?

[Cearbhaill]

I have a Ã"šÃ‚±4" crocea on the bottom of a 90 gallon (24" deep) tank under 8x54w T-5 lighting.

I know that recommendations all say that he should be kept higher up in the rockwork, but everytime I move him up he jumps back down. After having this happen time and time again I just left him on a rock on the substrate. He has been there since August of this year.

His color is good, excellent extension, no curling of his mantle, and he is laying down new shell at what I think is an astonishing rate.
Does this mean he is happy?

I read that things can appear to be fine while the clam is suffering, but wouldn't he stop growing if he didn't like the conditions?

 

[hwynboy]

no. I recently lost a teardrop that I had with great growth. It was about 7 inches when it died. I got it about 5 inches or so and it was growing fast....one day it closed up. I dont know why...but then I tried a few things nothing to get him to open up. All the while his bright white new scutes showing..he died a couple days later. While my Emperor and trigger and harlequin enjoyed a good meal. It was a huge loss for my reef tank. =\ Yet he was growing faster than any other clam in my tank.

 

[Cearbhaill]

Dang.
Is there any other feature that I should look for to determine health?

 

[Mr.Yuk]

How fast is a good rate of growth of new scutes anyway?