Clam sunken in shell

Kmst80 · Jan 10, 2025

Once Lights came on this morning i realized something is wrong with my maxima clam.
The clam has been in the tank for at least half a year and opened nicely until this morning.
I did a 10 % waterchange yesterday as i always do fridays with matching salinity and temperature.
I added the gorgonian behind the clam yesterday. Only other thing i did yesterday was changing the gfo. So after reading some threads mentioning to remove the gfo and put carbon in, i did that this morning.

It looks like the clam collapsed or is sunken within the shell.
Should or could i do anything else or is this a lost cause?

Miami Reef · Jan 10, 2025

Unfortunately it’s not possible to save it at this state. It’s too far gone. I’m not sure I’ve ever seen anyone save a clam once they’ve receded into their mantles.

Tahoe61 · Jan 10, 2025

Agreed.

Clams are famous for being sensitive to GFO and carbon.
Just to make sure it was not Pyramid Snails, I would check the base for the snails presence.
If the mantle had a ruffled appearance review pinched mantle disease.

mottomegl · Jan 16, 2025

Can you explain how gfo and carbon affect clams cause I lost a clam yesterday

minus9 · Jan 17, 2025

Can you remove it from the rock safely? If so, try a FW dip outlined in the sticky in this section for PMD. Looks like it had some growth.

Kmst80 · Jan 18, 2025

As mentioned by Miami and Tahoe the clam couldn't be saved. Took 2 days for the hermit crabs to start nibble on it and another day for it to dislodge out of its shell to be eaten by probably all the fish in no time.
A day after the post I saw what looked like the clam was spawning as a last ditch effort.
Rip beautiful clam.

minus9 · Jan 18, 2025

Sorry, I missed the timeline and sorry to hear about the clam.

Tahoe61 · Jan 18, 2025

mottomegl said:
Can you explain how gfo and carbon affect clams cause I lost a clam yesterday

A decade or so ago there were popular theories that the use of charcoal contributed to PM. Speculation was charcoal over polished the water, and altered the chemistry in such a way that detrimental to the clam. GFO was thought to do the same.
Bacterial pathogens have been identified as well as playing a part in PM. Introduction of infected Tridacna may spread the pathogen quickly to other clams.
Without scientific evidence I speculate that PM is a symptom rather than a single specific bacterial pathogen.

civber · Feb 6, 2025

Same happened to mine. It shrank, and after about a week or two, it was gone.

Arkayology · Feb 6, 2025

GAC does impact clams. I put some in my tank and the next day my derasa wouldn't open up. I removed it two days later and it came out a day later. Care is needed when using GAC and GFPO with clams.

minus9 · Feb 9, 2025

Arkayology said:
GAC does impact clams. I put some in my tank and the next day my derasa wouldn't open up. I removed it two days later and it came out a day later. Care is needed when using GAC and GFPO with clams.

Correlation isn't causation. I've used both without issue with clams. Maybe there were fines that made it into the display that irritated the clam?

Arkayology · Feb 9, 2025

minus9 said:
Correlation isn't causation. I've used both without issue with clams. Maybe there were fines that made it into the display that irritated the clam?

Except that I have a pattern that this has happened. 5 times over the past 15 years. Sure, it could be something else, but establishing a pattern is the first step towards causation. Others have experienced this as well. That's good enough for me at the hobby level.

minus9 · Feb 9, 2025

Arkayology said:
Except that I have a pattern that this has happened. 5 times over the past 15 years. Sure, it could be something else, but establishing a pattern is the first step towards causation. Others have experienced this as well. That's good enough for me at the hobby level.

I wonder if it’s a particular type of carbon? Or maybe the overall amount? I’m pretty conservative when using chemical filtration myself.

Arkayology · Feb 10, 2025

minus9 said:
I wonder if it’s a particular type of carbon? Or maybe the overall amount? I’m pretty conservative when using chemical filtration myself.

I'm using up the ROX carbon I bought 10 years ago. ROX is known for being very harsh apparently. It could be dust or maybe it takes something out of the water too quickly? IDK. Once that is gone, I will probably not buy more carbon as I find that it doesn't really help with much.

OrionN · May 8, 2025

It is the Carbon. Some of the carbon activation process apparently leave toxic residue. Look up problem with activated carbon several years ago, there were a lot of dead animals and tank crashes due to this problem.
About PMD, anything that irritates the clams will cause mantel retraction. PMD is only one of such problem. It’s onset, characteristic apparent and natural course discussed in my original writing.