Derasa Clam (Tridacna derasa)

Unfortunately, this clam also died. Interestingly, both my clams died after doing a routine freshwater dip. I have done such freshwater dips in the past without observing any negative symptoms though.

I suspect that I should have pH adjusted the freshwater or allowed it to thoroughly aerate before dipping the clam in.

This clam has begun exhibiting a localized mantle retraction.

A close-up of the inhalent siphon.

I removed all the vermetid snails I could find with some tweezers. The clam is semi-retracted now (second picture), perhaps in response to me partially removing it from the water.

A number of vermetid snails seem to have made their home on the clam. Unfortunately, they are quite close the the mantle and I think they will begin to affect mantle expansion. I'll have to remove them soon.

I have moved the clam a little bit in order to get a better view of the mantle.

The clam is exposing more mantle now and seems to have settled in.

The derasa clam is one of the larger and faster growing Tridacna species and can reach lengths of 1' 8" in the wild. It is primarily a sand-dwelling species and adult specimens eventually lose their byssus gland (which is needed to firmly attach to rock-work). It is typically regarded as the hardiest Tridacna and requires only moderate flow and good lighting, although it benefits from feedings of phytoplankton.

This clam hasn't fully acclimated yet and so the mantle isn't very extended. It's an unusual color for a derasa and I bought it before the LFS had a chance to acclimate it to the store's water, so I'm fairly sure it is suffering shipping stress as well.