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FAQs about Giant Clam Disease, Pests & Predators 6

Related Articles: Example Chapter from NMA Reef Invertebrates book, on Giant Clams, Tridacnids, A Brief Guide to the Selection and Placement of Tridacnid Clams by Barry Neigut, Bivalves, Mollusks, Lighting Marine Invertebrates,

Related FAQs: Tridacnid Health: Pinched Mantle Syndrome in Giant Clams by Dr. David Basti, Deborah Bouchard & Barry Neigut, Tridacnid Disease 1, Tridacnid Disease 2, Tridacnid Disease 3, Tridacnid Health 4, Tridacnid Health 5, Tridacnid Disease 7, Tridacnid Disease 8, & Pest Snails (Pyramidellids...),
FAQs on Giant Clam Disease by Category: Diagnosis, Environmental, Nutritional, Social, Trauma, Pathogenic, Treatments

Tridacnid Identification, Tridacnid Selection, Tridacnid Compatibility, Tridacnid Systems, Tridacnid Lighting, Tridacnid Placement, Tridacnid Feeding, Tridacnid Reproduction, Tridacnids 1, Tridacnids 2, Tridacnids 3, Tridacnids 4, Tridacnid Clam Business, Bivalves, Bivalves 2, Lighting Marine Invertebrates,

Tridacna derasa quarantine: 7/13/2009
Hi Guys!
Please forgive me if the answer to my question lies in your immense FAQs, but I was unable to find it so I thought I would just ask.
<Sure thing.>
I have just purchased a *Tridacna derasa*. I'm very excited as you might imagine. But, I'm confused with the quarantine. The clam is approximately 3-1/2 inches. I know that it is always recommended to quarantine for 2 weeks at minimum.
But, I'm a little afraid that it might attach itself to the bare tank bottom and I won't be able to move it.
<A valid concern, but easily corrected by giving the clam something portable to attach to, such as a old shell or a small piece of rock. >
I'm also wondering if placement in the display tank would offer better water flow, nutrients, and lighting.
<It would>
Would you still recommend a 2 week quarantine?
<If it is your only clam and you are certain that it is not carrying any parasitic snails that will devour it, yes, you can go ahead and put it in your display. Do watch it closely, particularly after lights out for signs of snails. If you had existing clams, I would quarantine it for the two weeks.>
As always you guys are the best!
Thanks for responding.
<My pleasure.>

Tridacnid HH 6/29/09
Dear Crew at WWM,
Thank you so much for all of the information you have here & the references, my husband & I have truly enjoyed learning about our beautiful tank inhabitants. Our original tank was last up 15 years ago so things have changed a lot since we started back in the hobby 6 months ago. We currently have a 125g tank, with spot on water parameters and all critters doing very well. My question is about a baby T. squamosa that I just purchased last week. Roughly 2" (5cm) long,
<Mmm, very small clams have a historically high incidental mortality>
beautiful caramel, honey, golden brown with turquoise spots--quite beautiful. Acclimated the baby, put it in quarantine, & introduced it to the tank--seems fine, mantle all the way over, reacts well to light, etc...as my hubby was feeding our plate corals & anemones, out of the inhalant siphon came a white worm looking 'thing'
<Might be a worm...>
about 1cm long 1/4cm wide. By the time I grabbed the camera to take a photo, it had disappeared. I have since spent hours trying to see this 'thing' since yesterday evening...can anyone help me with this description? I am horrified if there is a beastie in my baby or if it can reproduce and attach itself to any of our tank critters.
Many thanks in advance for your response, I truly do appreciate it.
<There are organisms that live as space "parasites", commensals for the most part... So send along an image if/when you can. Bob Fenner>

Re: My baby squamosa clam, not HH -- 07/01/09
Dear Kind Crew,
I wrote to you a couple of days ago with the query of a beastie being seen in my new baby squamosa. After spending hours watching the babe-camera in hand, I did move him up to the rock...Please find attached a photo & I would so appreciate if you could let me know if & what this moving 'appendage' is...
<The whitish object to the lower right? The excurrent siphon>
I await your comments--and thank you so much for the absolute invaluable advice you post--you're my favourite reference site!
Best regards,
<Do keep an "eye" on that urchin... can be problematical in poking clam mantles. Bob Fenner>

Coral and Clam Competing for Turf 5/5/09
WWM Crew:
<Josh Here>
I've been lucky enough to have the livestock in my reef tank flourish, but now I fear that I'm running into an issue where I have too many creatures competing for limited reef space. I've been able to somewhat successfully deal with this problem in the past, but now I'm in a bit of a pickle. I've attached a photo of my problem area. Obviously everything is attached to the rock, so I can't easily move anything. I'm most concerned about the clam getting stung, and I don't really care about the mushrooms or Zoanthids if they need to be removed.
<The clam may be getting close there... but they don't seem quite as close as you make it sound. Anyway, it couldn't hurt to separate them. While it certainly isn't ideal for the clam to be in contact with the coral, do Google search some for some photographs of giant clams in the wild, (often surrounded by corals).>
Will the clam survive if I allow it to be smothered by the Zoas and Shrooms, and if not, what is the best way to remove the Zoas and Shrooms. I'm afraid that scraping them away with razor blade will release toxins into the water. Thanks in advance for your help.
<Should be fine to scrape, if this rock is like most live rock, it may be just as easy to scrape away a layer of live rock with the corals attached as to scrape the corals themselves.>
<Good luck with the coral relocation...
Josh Solomon>

Tridacnid Maxima Disease 02/09/09 *Sorry, forgot to attach images in previous email* Hello WWM, I have searched all of the five pages on Tridacnid disease and have not found an answer to my question, so I hope that someone will be able to help me. My Maxima clam has been fine for months since I have had him (purchased tank Sept 08, Maxima came with it, in tank at least 6 months before that). In the past few weeks a brown colored film seems to be growing on the shell. <I see this> I have tracked its progress, and it is spreading. The clams behavior seems fine, mantle looks ok, it fully extends during lighted hours, but this recent development worries me. Please take a look at the two attached pictures and tell me if you can identify it. Thanks in advance. Landon <Need much more resolution here to tell... Could be a simple algal growth... of not much consequence... Perhaps a Hydroid colony... a Bryozoan... IF concerned, IF this growth appears to be deleteriously affecting the Tridacnid, I would take the clam out, and scrub the area (underwater) in a bucket of water outside the system. Bob Fenner>

Clam Question... I'm not seeing the problem 11/17/2008 Hi. <Hi Eric, Mich here.> I seem to be having some sort of problem with my clam. I thought it was the fact that that an angel was nipping at it, but that having been solved by removing the fish, I still see these grayish, whitish spots on the mantle. <Mmm, I'm not exactly sure what you're referring to here. I'm not seeing anything that looks out of the ordinary consistently in your pictures.> It started in one place about six months ago and progressed across the mantle. <The picture ending in 126 appears to be your clearest photo and the one I am relying on most here, but I'm not seeing anything that looks abnormal to me. Working from the outside of the mantle inwards, I see bright blue spots on dark purple, then a lighter brownish-purple, and then more bright blue spots. My guess is perhaps you are concerned about this lighter brownish-purple section, but this looks like normal color variation to me. When clams are moved into new environments/lights the colors often appear different.> I've looked for worms at night and have not seem them or anything else for that matter. <Mmm, I guess I'm not surprised?> I'd would appreciate it if you could lend your expert eyes to the attached pictures and hopefully offer a diagnosis. <I do not see anything that appears concerning to me, If I've overlooked something please let me know.> Thanks, Eric
<Welcome, Mich>

Re: Clam Question Clam Question... I'm not seeing the problem 11/20/2008 Thanks for the response. <Sorry, I'm not more help here.> I guess the pics don't provide enough color differentiation. <I'm just not seeing much, I'm sorry.> The spots are grayish white and it doesn't look natural. <Could be bleaching, which is the loss of the symbiotic algae known as Zooxanthellae, is sometimes related to changes in lighting among other things. More here: http://www.wetwebmedia.com/ca/volume_1/cav1i3/Clam_care/Clam_care.htm > However, since I removed the angel, the clam has started using calcium again, so maybe he'll be ok. <Let's hope.> Thanks again, Eric <Welcome, Mich>

Re: Tridacnid byssal gland trauma 11/16/08 Sara-Have another question for you, just FYI, the clam I have previously inquired about is doing very well, so apparently I was just overreacting. <Ah, cool> My next question however, is one I can't find an answer to anywhere. What are the general guidelines for stocking levels of Tridacnids? I would like to have several in my tank (30 gal w/ 15 gal refugium) but don't want to have them over compete for nitrates, etc. Is there a rule? I kind of wanted to add a crocea and derasa in addition to the maxima I currently have. Let me know! <Well, I honestly don't know of any real "rules" about it... but these animals are primarily photosynthetic. So they don't add to your "bioload" the same way fish do. Also, they grow at different rates (depending on the individual-- it's apparently a genetic thing). I imagine that how many you can keep in a tank depends on how fast they grow (since this will likely be the primary determining factor for how many nutrients they consume). If you can find some of the "slower growers" I think you could probably put as many in a tank as will comfortably fit. The problem is that you can't just look at a clam and know if it's a slow or fast grower. If I were you, I'd go to a LFS that's had some clams for awhile and ask them if they've noticed how fast or slow each of them has been growing. Explain that you're not necessarily looking for the fastest growing clam or else they'll like over-state the growth rates because they assume you want a fast growing one. In any case, I do think you could have 3 smaller (<6in fully extended) clams in the 30g tank. Even if they turn out to be super-fast growers, I'm sure you'd have no trouble placing (or even selling) it to someone else. The fast growers are more "in demand" as they say. Also note, if you're worried that your clams aren't getting enough nutrients, you can always just decrease the time you have the skimmer on. Also, please do pick up James Fatherree's book on ornamental clams... it's very good, and you seem to have the interest for it.> Thanks, Chad S <De nada... hope this helps, Sara M.>

Re: Squamosa death and Maxima Issues. 11/15/08 I went to the LFS today to verify everything. My salinity was a little higher due to the difference between my rinky dink plastic hydrometer and their refractometer but here are the parameters as of today... The tank is a 120 gallon with a 29 gallon fuge and ~30-40 gallons in the sump plus what is contained in the skimmer. KH=110ppm Ca=400 Nitrate=undetectable Nitrite=undetectable Phosphate=undetectable Salinity=1.027 ( I normally try to keep it around 1.025 or 1.026, I will be purchasing a refractometer soon) The only thing that I can figure is that the new Squamosa did not like the new flow pattern. The LFS guy said that trimming back the Montipora and the small movement of the powerhead changed the flow dynamics of the water. This could have caused the clam to exert what energy it had into moving <?> into a lower flow area and that led to it's demise? <Possibly> This sounds like it could be true but I wanted another opinion. He and I do not always see eye to eye when it comes to our views on husbandry practices. I have also down sized the picture of the maxima. <The Byssus doesn't look good> Another quick question, does Cyano bacteria grow in small patches... sort of like coralline. <Some species can, definitely> I thought I had some dark maroon coralline algae but pulled a rock out to trim some Acro and scratched at the maroon growth. It was not entirely soft but I could scratch some of it off. There is a small bit of Cyano started in the corner of the fuge, but it is the typical long stringiness. <Mmm, "comes" in a wide variety of shapes, colors...> I'm guessing this could be attributed to the skimmer issue I had ( will discuss in a second) and the maxima dying. I have done two ~15 gallon water changes in the past week and a half and plan to continue if this is a Cyano problem. I also swapped out my EV120 for my ASM G4. The EV120 injector was continually being infested by snail larva and not working correctly, so I ditched it but I fear that the multiple skimmer failures may have caught up with me. The growth in question is also in high flow areas of the tank, which I didn't think was characteristic of Cyano? <Again... Please read here: http://wetwebmedia.com/bluegralgae.htm and the linked files above... You'd do well to investigate RedOx potential as well.> Thanks again guys, Adam
<Welcome. Bob Fenner>

Giant clam malady? Mg toxicity -- 09/04/08 Hi Bob (and crew), <Hi Chris, Mich here.> Thanks for the many hours that you have collectively invested in the hobby and in this website. It is a great resource. <Thank you for your kind words here.> I am having a problem with the mollusks in my tank that I haven¹t been able to resolve after looking at the snail disease faq, the giant clam disease faq. or Fatherree¹s clam book. <OK, hopefully I can help.> My tank is a sps dominated mixed reef. Salinity is 1.024, pH is 7.8-8.1 (lower than I would like it to be) <Yes.> temp 78.5, ammonia, nitrate and nitrite are all not detectable, PO4 is around .25-.5 ppm (more than I would like), because of my high coral load and the presence of a large clam I am having trouble keeping my calcium and Alk where I would like them to be. My dKH hovers around six and my calcium is around 325. I know that these levels are too low and I am currently investing in a calcium reactor and Kalk reactor, which will be employed under the vigilance of an aqua controller to address this problem. My Mg is around 1300ish. <I think this maybe part of your problem.> I currently dose what seem to be excessive amounts of DT¹s 3-part calcium mg and Alk buffer to compensate for bio depletion and to raise pH. <OK.> Lighting is a 10,000K 250W metal halide. Tank turnover is about 50X. I have a 1 inch sand bed which I gravel vac as part of my weekly maintenance. I typically do at least 10% water change every week. (more often 25%). <Husbandry seems good.> I have great coral and clam growth and no algae problems. <Wonderful!> As for fish I¹m a fan of a relatively conservative fish load. I have a small flasher wrasse, a Banggai cardinal, a mandarin and a yellow assessor. (no coral eaters or clam nippers) <Great!> On to the problem: About a week and a half ago, my T. crocea (~5.5 inches) decided he was no longer happy as a clam. During the daytime, he remains mostly closed with his mantle mostly retracted. It does open ~75% in the mornings when natural sunlight hits his corner of the tank. It also seems to be expanded to a greater degree when the lights are off (~25%). The clam is still light responsive and appears to have no signs of pinched mantle, white spot, obvious necrosis or parasitic snails. It is located on a small rock on the bottom of my tank about 13² under water (mantle is at a 10² depth). It¹s byssal attachment is still quite strong. <OK.> I¹m concerned that he hasn¹t been opening. <Rightly so.> Since the situation arose, I have employed activated carbon in the tank in hopes of removing any DOC toxins that might be present and have done three 25% water changes in the past week and a half. <Well your carbon usage has likely cleared your water significantly, which may make your clam more sensitive to light.> I would be content to call this an issue related to the clams exposure to light in the tank BUT, I have noticed my Astrea snails have been remarkably lethargic lastly as well. <I think this is likely related to your high Magnesium levels and low Calcium levels.> One snail laid on his side half open for ~12 hours others have not moved for several days on end. I have not noticed any snail deaths. <Here is my theory: You are likely seeing paralysis from the high Mag levels/ low Calcium. Magnesium Sulfate (MgSO4) in the human acts as a central nervous system depressant. It blocks neuromuscular transmission by decreasing the amount of Acetylcholine released by motor nerve impulses. A secondary effect is the relaxation of smooth muscle tissue. MgSO4 is also the most commonly used tocolytic agent, it decreases the frequency and intensity of uterine contractions associated with preterm labor. It is also used to prevent seizures and convulsions..Mag toxicity is a huge concern in something the size of a human, let alone a tiny snails. When MgSO4 is given in a hospital setting the antagonist, calcium, typically calcium gluconate, is kept at the bedside. Patella Tendon reflexes are continuously monitored for signs of diminished or absent reflexes related to the risk of overdose. This is why I suspect your problems may be related to the Calcium level and Magnesium levels in your tank.> Any thoughts?? (sorry for the long email) <I do think this is a water chemistry issue. I think you should try raising your dKH, pH, and Calcium levels and lower your Magnesium levels.> Thanks, <Welcome,> Chris <Michelle Lemech MS RN>
Re: Giant clam malady? 10/8/08
Hello Mich, <Hi Chris,> Thank you for you well thought out response! <Welcome!> I think you are on to something. <Well, makes sense in theory I think.> In retrospect, I *think* I noticed more mantle extension on mornings after large doses of 2 part calcium buffer (without the Mg dose) and on mornings after CaOH was dosed. Depletion of calcium by mid morning could result in recurrence of the symptoms. <OK.> I had considered the idea of calcium depletion toxicity before, but discounted the theory because the clam was sill photo-reactive. I figured that adductor contractility would have also diminished if calcium was so low that it was interfering with either action potential propagation, cell signaling or smooth muscle contraction. <I suppose internal levels could be higher.> I have no idea about the histology of the adductor muscle. Is it smooth or striated? ( I guess this doesn't really matter.) In the past week my snails seem to have been doing much better. This is concurrent with your theory that this this is a chemical problem rather than a biological one. If I had some sort of pathogen in the tank the snails should have been the first to kick the bucket rather than get better. <Does support a chemical issue.> I am not sure, but I think I may now have a secondary protozoan infection. When the mantle of the clam is withdrawn (aka not midmorning when the sun hits the tank after a good shot of calcium) there is now a slight curl to a small portion of the mantle. When the clam is extended, here is no sign of pinched mantle what so ever. Do you think I should try and do a freshwater dip? <Mmm, think I would wait here.> Having decided that calcium depletion is a possible cause (and an issue that needs attention in my reef regardless, I am unsure how exactly to proceed. Specifically, I am wondering about adverse effects of GREATLY overdosing my system with 2 part buffer to increase the Ca levels. Do you know of any trace elements present in 2-part that will reach toxic levels if I am dosing WAY beyond the recommended dosage (as I would have to get levels where they ought to be) ? <I'm sorry but I do not have experience with this.> What do you think? <I think it is worth trying and just keeping a close eye on things.> Thanks again for your ideas and input! <Welcome.> Chris <Mich>
Re: Giant clam malady? 10/8/08
Hi Mich, <Hi Chris.> I wanted to give you a quick follow up Re my T. crocea. <Thank you. It is always nice to get follow-up!> You were 100% right. Last night I dosed more calcium than anyone ought to over the course of 8 hours and brought up my calcium 250 pts (now final concentration of 450ppm). <Yikes! Glad you did it over 8 hours!> The clam was fully opened this morning and has remained open all day. (for the first time in almost 3 weeks!) <YAY! Hope all stays happy and adjusted!> To you I tip my hat! <Glad to help.> Thanks so much for your insightful answer. Without your input the clam would have been chowder. <Yikes! No T. crocea chowder please!> Best,
<Cheers, Mich>

Giant Maxima Clam- What is this growing on it's side? 9/25/08 Hello, I have been researching something that I noticed on my blue Maxima Clam to no avail and am looking for some insight as to what is "growing" on my clam. I think it looks like a pale fleshy substance that slightly resembles the Exhalant Aperture of the Clam. This "growth" is round at the bottom and has an open spout at the top; it has not moved since we noticed it, and it is located on the ridge of the clam's shell and mantle. When the mantle is fully open it almost covers the object completely. When the mantle is drawn shut the object protrudes above the shell. I want to be sure it is not harmful, and if so if there is something I can do to help the clam. I have attached two pictures of the clam and the "growth" it doesn't not appear to have a snail infestation as we have not noticed anything else in or on the clam (although I have never seen such an infestation, and have very limited experience). Thank you for your help. Sincerely, Ashlee <Your photos are too small, unresolved to make this out. I suspect from your general description, shape of the object that this may well be a solitary Ascidian, a sea squirt. Please see here: http://wetwebmedia.com/ascidpt2.htm  and Part 2... I would leave this as is... not likely harmful. Bob Fenner>

Derasa Clam, hlth., comp. 9/24/08 Hello, this is my first question but I read your recommendations since a long time ago. Sorry my English is not perfect. <I understand you> My reef setup is running since a year and a half ago. Among many corals and invertebrates I have these two clams since a year ago. A derasa and I think a Crocea, but im not sure about that. The two clams where very good till now. The crocea is still very good but I see the derasa not extending the mantle as before like 10 days ago. I try to move the clam when I notice that the two shells were like disassembled and feels like the top shell was going to fell. <Yikes, no bueno> I leave the clam and not touched anymore. I was very careful and Im sure that I didn't do the damage. She opens a little and the color is good and sometimes close and open a little but Im not sure if she can recover by herself. Is not getting worse at least. I include a photo where you can see the two clams and you can see that the top shell is like a couple millimeters off the natural position. The water parameters are Ammonia 0 Nitrites 0 Nitrate 10 Phosphate 0 Carbonate hardness 8 Calcium 400 Temperature 80 I don't have a chiller and its a 30 gallon tank 196 watts PC and the calms are very high and in the center of the tank Thanks!!!! Fernando <I think this animal is being poisoned by either the Zoanthid below or the Polyp above. I would move either the clam or these stinging-celled colonies. Bob Fenner>

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