Clam died for no apparent reason

[billdogg]

Like the title says - One of my two maxima clams died and I con't figure out why.

I've had both of them for at least 3-4 years and they've always done well and grown considerable. About 3 days ago the smaller of the two was very withdrawn, and by the next morning was beginning to gape. I pulled it today although the outcome was obvious yesterday. I took it outside and inspected it as closely as I could. I found a single very small snail that might be the culprit but could no others like it on either the dead clam or the one that is still seeming to thrive.

The tank - 120DT/40 sump setup since 2013 but some of the sand and much of the rock date to the late 80's/early 90's - it is without a doubt a well cycled tank
Skimmer - RO150sss
2 x AI Sol blues set to 45W/65B/65RB 12hrs on/off
2 x 250 gyres at about 60% and a couple koralia 1500gph for those pesky dead spots in back.

Water parameters are as follows: All test kits are Salifert
Ammonia/Nitrate undetectable
Nitrate - just a very slight color change, barely detectable
Phosphate barely detectable
Calcium - 400
Alkalinity 8.9
Mag 1350
Salinity 1.024
temp 78

Any ideas?

Thanks in advance for your help!

 

[Reef noob_]

Were they low in the tank? Clams can be slowly suffering from low or poor lighting then die and be consumed quickly.

Sent from my Pixel 3 XL using Tapatalk

 

[OrionN]

Are there white new growth on the shell? Both clams?

 

[MondoBongo]

are your AI Sols functioning properly?

i lost my Derasa clam a few months back. i had it for several years. turns out my AI Vegas were having a problem with their driver board and shutting off pucks for long periods of time, probably due to overheating or something as near as i can guess?

i hadn't noticed soon enough, because it was only happening intermittently, but often 2 - 3 of the pucks would shut down.

 

[billdogg]

The lights seem to be fine. No oddities growing a n either clam that I can see. The surviving clam, the larger of the two, seems to be fine.

They have been on the sandbed since day one, fully expanded and growing nicely.

 

[Uncle99]

Is there anyone who might have had lunch?

Some Angels, wrasses and peps have been known to nip, and once tasted.....clam meat is very tasty.....you have a settled clam in an on point consistently stable water....should not have gone so suddenly....