7 clams dead in 3 weeks

You added a couple clams recently. Back in the Clams Direct days it got real. Some wierd virus wiped out a ton of tanks and no one could find anything conclusive. QT new clams for a long time.

 

The only thing that jumps out is your photo period. 6 hours is very short.
I'd go 10 hours for day lights and 12 hours for actinics

 

The last one to die appeared healthy. Almost like it died over night. I shortened the light period about 3 months ago. I didn't figure it would kill them. I only cut back 2 hours for each.

 

Exactly the same thing happened to me. The would look good one day and be dead the next. Sometimes they wouldn't fully expand their mantel but it wasn't PMD, then look great the next day.

 

sorry for your loss

 

if your are sure there are no natural predators present in the tank then you dont have a million possibilities.

either your tests are old and not showing correct values or, and i think sadly this is the most probable, you have some sort of disease/parasite.¨

bonne chance!

 

i lost a clam or two to some hitchhiker predators/a "snail" the LFS sold me! So, be sure you dont have any rogue agents in there. Or as swiss says, there arent many options left.

 

Since you haven't added anything new, I would look to the decrease in the lighting period. I would consider decreasing a clam's light by 25% to be significant.The derasus clams still being alive could be proof of this since they tend to require less light than the others.

 

Any update on this thread? Have the last two clams survived I hope? Any new information regarding the cause?

 

Haven't lost anymore. Last 2 big clams see healthy. Tank seems stable. Increased my photo period by two hrs. Waiting to see what happens. Thanks for the inquiry.