help with slowly retracting crocea

[johara]

My three and a half year old crocea has been gradually expanding less and less over the past four months or so. It is 3 1/2-4" in size, sits on the sandbed 26" under a blend of 250W 10K and 400W 20K radium halides. I haven't fed it DT's in over a year as I read that once they are over 3" they either don't need or maybe even can't use phytoplankton any more. THere are no other clams in the tank.

It was infested with pyramellid snails about 2 yrs ago, but recovered completely and I don't see anything now. I tried covering it with a strawberry basket in case a fish or shrimp was harrassing it without me noticing, and that didn't make any difference. Yesterday I was reading about "pinching" and thought perhaps that was the problem and did a careful 30 minute fresh water dip. Today it looks about the same, perhaps even a bit more gaping. I did note 3 asterina stars fell off with the fresh water dip, but I don't think they are known to bother clams. Today I gave it some fresh DTs in a bowl of tank water, it didn't seem to ingest any and contracted even more. I hope I'm not "killing it with kindness".

Water has no measurable nitrates, trace phosphates, KH ranges 9-11, Ca 400-440, pH 8.1-8.3. Temp ranges 79-81. Tank has been up three years. THe clam was in a 55G previously which has now been upgraded to a 155. I'm a bit mystified about this downward trend after so many years doing well. I have been a bit more conscientious about water changes and overall quality in the last year or so, maybe the clam preferred slightly more nutrient rich water? Maybe doesn't like Phosban? Some infection?

Any ideas would be much appreciated! Here's some pics from now, and a year ago at full expansion.

 

[iceman16238]

does dt's. even large clams(1'+) eat it on the barrier reef.

 

[johara]

Would you suggest bowl feeding or dosing the whole (155 gal) tank? As I mentioned I tried bowl feeding today and the clam seemed to react badly, contracting further. If I feed the whole tank - how much dt's? Seems like it could get expensive to get enough for the clam in that much water!

By the way - is that considered gaping in the first picture? If so is that an even worse sign than the mantle retraction? I'm told croceas often have that gaping look even when normal, but I don't know how much is ok.

 

[iceman16238]

didnt realize how big ur tank was. You will stress the clam more than it already is if you put it in a bowl. Feed the whole tank. put enough that the water has a green tint.

 

[mbbuna]

move the clam half way up in ur tank into the rockwork.it looks a little far gone i dont think it will make it sorry to say. also stop the phosban for now, also do a 10-20% water change. good luck

 

[johara]

Thanks for the suggestions. I had already moved it up. The phosban is due for a change, so I'll hold off on that for a bit. A water change never hurts though this is clearly not an acute event, the clam has looked like this for weeks now if not months. I've never known a clam to have such a slow decline. They're usually fine one day and gone the next. THat's why I thought maybe it was stopping the DT's that caused slow starvation. I've resumed those feedings, but as you say, it may be too late.

 

[mbbuna]

i suggested the water change because I've had strange-bad reactions with phosban

 

[johara]

ok- gotcha.

 

[JHReef]

didnt realize how big ur tank was. You will stress the clam more than it already is if you put it in a bowl. Feed the whole tank. put enough that the water has a green tint.

Isn't that just a bit extreme? I'd only do the recommended dosage unless you really don't mind throwing the water chemistry out of whack. JMO.

 

[johara]

Yeah, I thought that sounded like a bit much and have been going with the recommended dose. I don't need an algae outbreak. By the way do people shut off the skimmer when dosing DT's?

The clam remains almost exactly as in the first photo - no better, no worse.

 

[mbbuna]

i leave my skimmer on when i add phyto

 

[iceman16238]

Isn't that just a bit extreme? I'd only do the recommended dosage unless you really don't mind throwing the water chemistry out of whack. JMO.

Nope. You probably just misunderstood when i said green tint. I should of said slight green tint?????? Anyway, i have a tank full of colorul sps. I used to dose dt's 2-3times a week and had no algea outbreaks. Or maybe i am just color blind . The recommened dosage is what turned my water slightly green. I think i was adding like 3 capfuls each time. I have 5 clams btw all are healthy and growing(especially my blue spot squamosa ).
Phosban,rowaphos, and phosguard are nono's as far as im concerned. I have seen what devistation they reak of sps. Good luck man.
Ohh yea, i leave my skimmer on also.

 

[johara]

iceman - why did you stop the dt's? How big were the clams when you stopped? Any change in health or growth rate of the clams when you stopped?

 

[iceman16238]

iceman - why did you stop the dt's? How big were the clams when you stopped? Any change in health or growth rate of the clams when you stopped?

I felt that my clams were at the size where they do not require it. I have had all the clams i had for over a year now. All started at about 3-4" and now my maxis are about 6" and my squamosa is like 10". i did notice a slight decrease in growth. I dont mind though. i have no room for the squamosa to grow . Health is fine without dosing at the current size. I stopped dosing simply because i did not need to after they reached a certain size. Plus more food in the tank=more nutrients for algea(luckily i never had an outbreak). Maybe thats because all the phyto was being used up????????? My squamosa is a beast. Check the pics in my gallery if u want.

 

[Snprhed]

Dosing DT at the prescribed rate will not affect water quality. Its not like all the stuff that sits on a store shelf for months at a time. It is a live culture.

 

[johara]

Thanks for the replies. I enjoyed your clam pics iceman. I really don't think my clam problem is from stopping dt's, but I figured it can't hurt to cover all the bases. The prescribed dt dose does not discolor the water any, seems like it's a pretty minimal amount, but I assume the dose is based on measuring phytoplankton/cc of water so should be correct.

I did move the clam half way up the tank under 400W halides, so light should also not be problematic. It's off the sandbed now so critters munching shouldn't affect it. I don't really have any idea what the problem is - it just stays retracted all the time and has for months. I may repeat the fresh water dip about a week after the last one just cause I can't think of anything else to do. I'm reluctant to add new clams even though I'd like to as I haven't diagnosed this problem and thus don't know if there's some tank condition that could affect new clams as well.

 

[iceman16238]

Why don't you send an email to barry at clamsdirect. he might have a better idea of what you can do.

 

[Snprhed]

Good idea Ice

 

[johara]

I did post at clamsdirect but no one there knew either. I didn't directly e-mail Barry as I didn't get the clam from him, but I could try that. Thanks.

 

[Barry N.]

johara, sent you PM.