Shell Shocked

[stalefish]

I just had 5 clams die in the space of about 30 hours - all virtually spontaneously. By that I mean, they looked fine when the lights went out, but then in the morning they were just wilted in their shells - 1 found the first morning, 2 a few hours after lights out the next night when I noticed a bunch of nassarius' on them and two more the next morning. The fish, corals and other inverts are just going on as if everything is fine, just the clams seem to be affected.

The tank's a little over 100 gallons in the display and about 135 total water volume. Water parameters are as they have always been: PH 8.2, Salinity 1.026, temp ~80.5, phosphates - undetectable, calc ~ 380-390, ammonia - 0, nitrates ~20, nitrites - barely detectable. RO/DI water always used for everything. I've been doing a 25% water change every week or two, so there's nothing new there.

My feeling is the nitrites are probably a result of the clam deaths and not the immediate cause. Nitrates are higher than I'd like, but have been stable at this point for a while and my understanding is that's not too high for clams. Tank is about 7 mos. old, some of the clams have been in there since early July, others are fairly new. Varying sizes and species - croceas and maximas. I had a derasa experience something simliar about 3 weeks ago. I got him out of there fairly quickly but it was too late to save him, and I just chalked it up as one of those things since everything else seemed fine at the time.

What's puzzling is that they just all died so quickly, like a virus or mass clam suicide or something. The remaining two clams looked fine so I got them out of there and into a 'hospice' tank and they still looked ok as of this morning.

No signs of parasitic snails. I'm very puzzled.

I guess what I'm looking for is if anybody else has heard of this and some help in how to proceed. My current plan is to let the tank go fallow of clams for a while, but I'm not sure how long that should be. 1 month, 3 months, forever? Any help appreciated.

-Don

 

[DonW]

I would guess long term poor water quality. 20 long term is to high. Did you have a temp swing? Do you use a temp controller?

Don

 

[Snowboarda42]

Its like a Clam-cult-mass-suicide

What types of corals are you keeping in the tank? Whats your lighting like also? Photoperiod?

 

[krisfal]

Was the deresa that died 3 weeks ago a new addition? If so I wonder if it could have brought something in? For all the clams to die in such a short time period it seems like the cause was something they were all exposed to at about the same time, not a long term problem where you would expect a slower die off.

Any unusual chemicals in the house refinishing furniture, painting etc? I know someone else here on this forum had thier clams die off rather quickly after some pennies were unknowingly dropped into the tank and began to dissolve.

I do not know much at all about clams but to lose 5 clams in a little more than a day it seems like something caused a major change in the system. Sorry to hear about the loss!

 

[stalefish]

The derasa that died was around for about a month.

I agree the nitrates are high - I'm working on it - but I don't think all (most) of the clams would just die virtually simultaneously, but rather I'd see some other signs of decline first and I'd think the newer clams would last longer than the old if that was the cause.

For corals there are some acroporas and montis, some brains, and various other things that are still looking happy as a ..., um, well, still look healthy. I would think the corals would be more apt to be the canary in the mine shaft than the clams which is why I'm thinking it was something specific to clams.

Other interesting thing is in all cases it happened overnight when the lights went out. I have a refugium with the reverse daylight thing going on and have measured my oxygen levels at night and they're always fine.

Lighting is Solaris LED (awesome lights btw) and the photoperiod automatically adjusts with the seasons but is always in the 12 hour on range.

The two survivors (maxima and derasa) are still doing well in their hospice tank. The only thing different about those two is they were slightly removed from the others. One was higher in the rocks by a bit and the other was out in the sand at the end of the tank. Still, it's a 60" tank and clams on both sides were affected.

 

[Barry N.]

I think we would just be guessing as there is so many reason why this could happen.

Introduction of new animals.
pH, salinity or other chemistry swings.
New brand of buffers, i.e ( salt, suppliments)
Not washing your hands before placing into tank.

 

[stalefish]

So my derasa in the hospice tank died this morning - same thing, except since I've been watching him so closely, I noticed he didn't seem to extend all the way out yesterday.

There's nothing in common between the display tank and the hospice tank - I even purchased the water from my LFS since I didnt' have any ready at the time.

I've felt all along I'll never know the real reason behind this - one of the more frustrating aspects of this hobby.

If anybody has any ideas on anything I could do to save my last clam - he's a beautiful teardrop maxima and I'd really hate to lose that one. He looks fine at the moment, but then they all did.

The other question is on the display tank. Other than getting my parameters in order, I'm going to leave it clam free for a month or three. Any advice on the duration for that or any other steps I can take to get it clam safe again?

-Don