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FAQs about Giant Clam Disease: Environmental

FAQs on Giant Clam Disease: Tridacnid Disease 1, Tridacnid Disease 2, Tridacnid Disease 3, Tridacnid Health 4, Tridacnid Health 5, Tridacnid Disease 6, Tridacnid Disease 7, Tridacnid Disease 8, & Pest Snails (Pyramidellids...),
FAQs on Giant Clam Disease by Category: Diagnosis, Nutritional, Social, Trauma, Pathogenic, Treatments

Related Articles: Tridacnid Health: Pinched Mantle Syndrome in Giant Clams by Dr. David Basti, Deborah Bouchard & Barry Neigut, Got Tridacna? A beginner's guide to keeping Tridacnid clams by Laurie Smith, 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 Identification, Tridacnid Behavior, Tridacnid Selection, Tridacnid Compatibility, Tridacnid Systems, Tridacnid Lighting, Tridacnid Placement, Tridacnid Feeding, Tridacnid Reproduction, Tridacnids 1, Tridacnids 2, Tridacnids 3, Tridacnids 4, Tridacnid Clam BusinessBivalves, Bivalves 2, Lighting Marine Invertebrates,


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>

Questions about crocea clam and an open brain coral -02/06/08 Good afternoon, I hope this email reaches you all well. I can't tell you much I (we) appreciate what you do for us! Anyway, I have two questions I have searched for on WWM archives (there's A LOT) and can find no clear answer for. In fact, I'm a little confused. First, I have a question about a red open brain I got last week. Picture attached. In the week I have had it, I have seen no movement, no tentacles, no feeders, no nothing! It has also lost a little color since I got him home. Last night, I saw slime tentacles with little bubbles on the "slime" which were extended about 4 inches above him. Is this normal for a while as it gets used to the tank? <Usually, yes, it can take some time for feeders/sweepers/etc. to come out.> The only other invert near him right now is a small rose bubble tip 8 inches away and up in a rock crevice. Also, on many WWM archives, these should be placed directly onto the sand bed , which mine is. But, I saw some other WWM archives that said to place it into a rock structure, since it gets irritated if sand is blown in it http://www.wetwebmedia.com/trachyidfaqs.htm Which is it? Sand or rock? <On the sand is preferable. However, if it keeps getting covered in sand, you might want to prop it up on a rock.> Second question, I also have a Tridacna crocea clam I bought at the same time. When I placed him into the tank, I also placed him into the sand with a piece of tile 1/4 inch under him in the sand (did my research!) so he could put his foot onto something, and although he looks very healthy and opens / closes as he should, he keeps "knocking" himself over onto his side. I don't want to keep adjusting him and causing more stress than he probably already has. I know he should eventually be moved onto a rock, I just wanted to keep him where he is so I don't "light shock" him before I move him up. Any suggestions? <The tile might be too flat or not the right size/shape for it to "balance" itself on. Try a rock or some other hard surface that it can sit balanced on.> Is he OK on his side? <Not in the long term.> The sand grains you see in the picture get blown out when he "exhales" (which is what is knocking him over). I hope these don't seem like silly questions.) Tank specs: 55 gal (w/10 gal partitioned sump holding Chaeto algae) 4 inches of Aragonite live sand 40 - 50 lbs live rock 3 Ocellaris Clowns (introduced together last year) 1 Clarkii Clown (plays nice with the O's) in a Sebae Anemone 1 Bubble tip Anemone 6 nice stalks of Xenia (doing very well I might add) 1 Sailfin Tang 1 Six Line Wrasse various Zoos (small colonies) Nassarius Snails and various small hermits, lots of amphipods, copepods, and a few bristle worms the wrasse has yet to find. PH = 8.4 (evening) Ammo, Nitrates, Nitrites, Phosphates = 0 (hard to believe on the last two, but that's what my test kit says) Calcium 460 - 480 Alkalinity = 11 - 12 Magnesium 1300 - 1400 Shayne McKean
<De nada,
Sara M.>

Can Cyano kill clams? Oh yes   10/2/07 I have a 55 gal saltwater aquarium. I'm having a bit of a problem with Cyano. I've repositioned my powerheads so that there is water circulation in all directions. <Helps> It seems to have gotten much better except on the substrate around my Crocea clams. I purchased a few queen conch, <Get too big...> some snails and a sand sifting cucumber <What species? Some of these aren't "reef safe"> to keep my substrate stirred up. I even stir it up myself and try to siphon out the Cyano. <I would do this VERY carefully> My question is this. I came home from work to find the mantle of my clams rather withered and retracted. Upon closer inspection I noticed I could see right through them to the substrate. Could the Cyano bacteria on the sand have caused this or is it more likely my cleaner shrimp or emerald crab (even though I've never caught them in the same area as the clams) <Could be the Mithraculus for sure... but also the BGA is a negative influence. Have you read on WWM re various means of countering Cyano profusion? I would. Bob Fenner>

Did my new lighting kill my 4 year old Tridacna maxima -- 09/12/08 Hello, I had a Tridacna maxima for about four years. Purchased it about 3" in size and it grew to 6" over the last 4 years. The clam had always been healthy. My tank is a 55gallon reef w/25 gallon sump, Only additives is Kalk Drip ½ tsp per gallon of top of water and trace elements through bi-weekly 15 gallon water changes. Also use Phosbuster. <... this is the most likely "causative agent" thus far... Clams, all live need phosphate...> Calcium runs from 325-380 (maybe a bit low). <Yes> PH 8.1 -8.2, Salinity 1.022, <Too low...> no Nitrates, Nitrites or Ammonia. About two weeks ago I removed two of my four 96w Power Compacts 10k/Actinic Smart Bulbs and added two 250w 20k Metal Halide. A grand total of 692 watts. Transition- I ran the two power compacts 2 hours then shut off and turned on the MH for 1 hour and then Power Compacts on 2 hours. I increased the MH duration 1/2 hour each day until they were on a total of 4 hours per day with the Power Compacts on for 4 hours per day. I noticed that the clam was barley opening on the second day of transition. Figured it was adjusting to the light. <Mmm... maybe not> After two weeks I noticed that a whole bunch of my blue legged hermit crabs were eating it from the mantle down. <Oops, yum!> I removed it from the tank yesterday because it appeared close to death and did not want to poison tank. I was wondering if I killed it with to <too> much light? <Maybe this along with other stress sources, yes> The clam was always at the bottom of the tank so it got less light then the rest of the corals <... Clams are not corals> in the tank which all seem to be fine with the exception of my Rose Bud anemone. It seems stressed, eating fine but is shrinking and expanding and is also wanting to move to somewhere else in the tank because it is releasing it foot to try and move. Something is obviously amiss. <Yes... again, the light, HPO4, spg... of what you mention> Aside from the lighting the only thing I have changed in the tank was adding a medium size frag of sun corals and small Acropora frags. Oh almost forgot I have been able to maintain tank temperature of 75F-79F with the halides by use of a fan. Tank is 75 when lights turn on and 79F when lights go off 8 hours later. The Metal Halides are CoralVue Mogul Base style, retrofit so they don't come with a UV shield. Do they need some special UV glass between them and the tank? <Uhh, I'd be contacting the manufacturer re... More and more such lamps come with a coating on their glass, but I strongly encourage all to provide another layer/barrier between the water and the lamps... for safety's sake... to prevent damage (even explosion) from splash, spray> My plan is to do a large water change this week, 55 gallons of the total 80 gallons of water volume, just in case something is wrong. Could the clam had a predator that I could not see that was introduced from the sun polyps or Acroporas or did I introduce the new lighting to fast or likely something else in water? <Doubtful re the predator, but the three items mentioned above... for sure> Any insight into what may have killed my clam would be appreciated. It was one of the oldest things in my reef and really disappointed that is now gone especially when they can live so much longer than that. Brian <I'd ditch the chemical filtrant, raise the spg, use a more gradual photo-acclimation process. Bob Fenner>

Gigas clam health failing!!!!!!!!!!!!    5/12/07 Hello Bob & WWM crew, <Antonio> I have an 18in. Gigas clam that I bought 5 days ago. <Wowzah! I guess/hope you have/had a strong back!> I acclimated the clam well & placed him in my 150 gallon reef,  (48x24x30)! Water parameters are fine, PH 7.8(Which I wondered if it was too low), <Yes> and no other traceable problems in water quality. <Actually... whatever would occasion/cause the pH of this system to be this low is VERY big trouble> This tank also houses 9 other Tridacna clams, 13in. derasa, 10in. derasa, 8in. derasa, & a few others, squamosa(2), blue maxima, and one crocea. <... I would NOT mix all these species together...> The lights are 2 250W 6500K Iwasaki's, 1 175W 10,000K Red Sea bulbs! The new gigas clams mantle is starting to recede which I know from experience is a sign of impending death. His reflexes are still very good but I  can see clearly that he's on his way out! <Mmm, not necessarily... Is very likely still adjusting from the move...> Do you all have any clue as to what the problem may be? Antonio <Is/was this animal wild-collected at this size? I do hope not... If it was moved from someone else's system you need to talk with them, compare notes re feeding, water quality, light quality/intensity... For review, please read here: http://www.wetwebmedia.com/BookMatters/WWM/NMA-RI/NMA-RI_Tridacnids-demo.pdf and here: http://www.wetwebmedia.com/tridacnidart.htm for the links to the files above on Systems, Diseases of Tridacnids. Bob Fenner>

Unhappy Tridacna squamosa...Too Much Light Too Fast? -- 05/09/07 Hello, <<Howdy>> I purchased a 5 year old Squamosa (about 6-inches) approx 7 days ago.  I  did a two-hour drip and it acclimated very well for the first day.  The  second & third day it didn't want to open much, so on the fourth day I gently nestled a rock under it so it could foot hold. Almost immediately it opened up beautifully for about two days.  Now yesterday and today it is gaping on and off and the interior of the clam seems sunken in. <<Mmm...>> It is open and the mantel is out and the clam is very  responsive. <<A good sign>> Also the color looks good.  Is it doomed or can I do anything? <<Theirs is usually little we as hobbyists can do for these creatures once they show signs of decline, but if the decline is attributable to an environmental situation that can be identified and corrected  the clam may pull through if not too damaged/too far gone>> It was raised under VHO lights and is now is in a 75 gallon with 2 250-watt metal halides. <Ah!  A definite clue...  If the clam was not acclimated to the more intense lighting it is likely suffering from photo-shock.  You can try shading the clam a bit with layers of fiberglass window screen or the like (have a read here and beyond for more info: http://www.wetwebmedia.com/acclimcoralslight.htm), removing a layer every couple days to allow the clam to become accustomed to the new lighting...though since it has been more than a week since the clam was placed under the halides, this strategy may now be a moot point>> Ammonia 0 Nitrite 0 Nitrate <5  Phosphates 0 PH 8.4 SG 1.024.  I have a lot of sensitive corals like Alveopora and  a Crocea and Maxima and they are well so I don't believe it is the water. <<Then is likely the lighting>> Its bottom dwelling neighbors are a 3 plate Fungia  about 3-5 inches away and the other side a Lobo about 4 inches away.   Any help would be great. <<Do also have a read of this article by Barry Neigut of Clams Direct on selection and placement of Tridacnid clams (http://www.wetwebmedia.com/ca/cav1i3/Clam_care/Clam_care.htm ).  Regards, EricR>>

Why are my clams losing color? Hi guys! I have 8 clams (left) only lost 2 in 5 years, 1 was only 1.5" the other I made the mistake of moving too many times. (7" Derasa) Have Maximas, Croceas and 1 Squamosa. (all are 3-5") They were in my 75 gal reef w/ 2-175 wt/10K MH & 1-130wt act. and doing well. I decided to make a small "clam tank" out of a 20 gal. tank that no longer had any residents, but has been set up for about 3 years. It is a very stable tank for a 20. 2.5" of fine sand, a bunch of Nassarius snails, Cerith snails, 4 Turbos, 6 Scarlet hermits, 2 small Rio's, a Prizm skimmer and now a 150 wt/20K HQI MH pendant about 6" from the surface. Most of the clams seem to be doing well except 2, a blue Pohnpei Maxima and one of the Croceas that's solid purple. They seem to be losing some of their color at the edges slowly. Some lost a little color in the 75 gal until I started adding a little Iron/Mang. supp. and then that seemed to help them regain the color. (even 1 that arrived a little bleached) The bleached tissue looks healthy except the pigment/Zoo is going away. I give the same supplementation variety as the big tank (proportionate) but I'm wondering if the smaller volume requires more or less of something. << Well here is where test kits are important.  You may have had something adding or removing the magnesium from your old tank.  The best thing to do, is to not worry about how much you are adding proportionally, but what the actual levels are. >> I used to use all SeaChem stuff but after having a problem keeping my alkalinity consistent (with the 2 part cal/carb) I started using Kent Liquid Reactor. It is so much easier to use and doesn't make the alkalinity go up and down. (switched months B4 moving the clams) Any ideas why the clams would lose their color in this situation. << I believe most clam color is due to lighting.  It is very difficult to replicate lighting from one tank to another.  I'm assuming you are using the same type of bulbs, and the clams are the same distance from the bulbs, but even with that it is tough to say. >> I don't think it is a light issue. Does the calcium level have any bearing on coloration? << Not as long as it is in that acceptable range (250-600). >> Is the Prizm too much skimmer for this little tank? There are 2 Gorgonians in there with them (Sea Whips-purple and red/yellow) and they are growing like crazy. << Well now this may be the case.  Clams do filter feed much.  So it is okay to skim heavy, as long as you are feeding them as well.  I don't like to advise people to turn down/off their skimmers, but this may not be a bad idea for you in this situation. >> I feed them all Liquid Life frozen plankton every other day or so, a little Iodine, the Iron/Mang. SeaChem liq. calcium and the liquid reactor twice a week. No, I haven't read Daniel's book yet but I'm going to order it now. Thanks for any help! Scott << I guess I would also say that an iodine and magnesium test kits wouldn't hurt. >> Scott Howe        <<  Blundell  >>

Clams In A Jam? Afternoon all!! <Hiya! Scott F. at your service!> I have an issue with my two clams as of the past few days they are only ? open. I have had both for years and all other corals and fish are thriving. Is this common in clams. My calcium reactor is working throughout the day and all parameters seem fine. Of late the clams have been emitting some kind of mucus which I assumed was from the newly added calcium reactor. Any advise on why BOTH they have shut for the past two days?? Thanks Stu <Well, Stu- it's hard to say exactly what your clams are reacting to, but it might be possible that some sort of water parameters are out of whack. Usual suspects include ammonia, nitrite, excessive phosphate levels, or rapidly fluctuating pH, not to mention the possibility of "chemical warfare" from stinging cnidarians that may be in close proximity to the clams. Did you recently change lighting? Are you using any new additives, "medications", or foods in the tank that could be a problem? Test the water again, just to be sure. In the absence of these as problems, the other possibility is that someone in the tank has started picking at the clams. Do check the behaviors of any of the "usual suspects" (i.e.; angels, certain wrasses, etc.) to see if this occurring. My advice when these kinds of seemingly unexplained anomalous behaviors occur is to use the old standby of a water change, coupled with use of aggressive protein skimming and activated carbon. Hopefully, with a bit of minor intervention, and the passage of time- things should work out fine, and they'll be "happy as a clam" in no time! Good luck! Regards, Scott F>

Derasa Clam Problem Bob, I have about a 5 inch derasa clam and a 2 1/2 in maxima clam. I have had the derasa for over a year and it has been doing very well. I just recently added the maxima about 3 months ago. To give you some info on my system, I have a 125 gallon reef tank with a mixture of hard and soft corals. I have VHO lights. All of the necessary parameters for good water quality are where they should be. Both of my clams are on the floor of my tank. About two days ago I noticed my derasa clam was leaning to one side, which I didn't think much of because it sometimes would tip over because a fish would swim by and spook it. I went to straighten it up with a little stick I have like I have done hundreds of times before and noticed that the clam didn't close right away from the contact. As a matter of fact, it almost seemed like the two halves of the shells were not aligned anymore either. When I tried straightening the clam by lifting the one half of the shell it sort of moved independently of the other one. This seems to have gotten worse over the last few days. The mantle is not receded or anything and still has good color. The clam just isn't opening up fully like it used to and the what holds the two halves together seems to have lost the strength to hold itself together and close fully. The clam is showing no signs at all of being attacked by anything. I see no holes from worms. There were a couple of those supposedly reef safe snail with the small, flat, purple and brown shell that only come out at night hiding underneath the shell but I'm pretty sure these are not doing anything to the clam. <if you are referring to Stomatella "paper-shell" snails then I agree> I know it may be hard to determine the cause of the problem but do you have any idea what would cause this?  <I'm concerned if the clams were kept on the sand bottom without a rock buried underneath them. Attachment to a small rock is critical... it prevents snails, worms and crabs from preying from below through the vulnerable abductor port/muscle. Pyramidellid snails are very tiny (like grains of rice as adults!) and very damaging over time. Another concern I have is the lack of light at depth... I fear the clam has been starving from inadequate light. As bright as VHO lamps seem to be... they are very weak at depth: they are only good for the top 12" of water and degrade rapidly below that. So if the clams are at the bottom of an 18-24" deep tank... they are not getting enough light. Starvation may be an issue here> Is there anything I can do to reverse whatever is happening to the clam. If not, should I immediately remove it from my tank before it maybe spreads to my other clam which sits right next to it?  <unlikely to be contagious... look for Pyram snails and other predators (crabs, bristle worms) and move the clams to within the top 12" of the surface> I appreciate any help or advice you may offer on this problem. Thank you, Gianluca Carpinelli <best regards, Anthony>

Clam question Bob, I'm back with additional questions. I have 2 75 gallon tanks both with PC (4 55 watt -7100/6700K on one tank and 4 65 watt - 8800K/7100K on the other tank). I'm having problems keeping clams for long periods of time. (Nitrates, nitrites, ammonia, phosphates are 0, ph 7.9 - 8.4, Calcium is 400-450, Alk 9-10, salinity 1.023 - 1.024, oxygen is at saturation, temp 78 - 80). <Mmm, could be a few things... including a need for more light (or moving the animals up in the water column), foods/feeding of the clams, a lack of phosphate... got to have some> I've had one derasa clam (4 in shell) that has survived for 2 years now and has always looked like it was thriving and continues to do so - its added 1 - 2 inches in shell growth since I purchased it. I've had a maxima (3 in shell) that thrived for about 8 mo.s, and then suddenly died. I've also had several baby Maximas (1in) - roughly a dozen - and around another dozen or so small crocea/Maximas/squamosa/derasa (2 in) that have also died. Basically, they appear to thrive for several weeks, and then they all appear to become ill and die within 1 week: - initially, they fail to extend their mantle much past the shell edge. - then they start to show 'gaping' on their inlet siphon. (within 1 -2 days) - then (within 1-2 days of the 'gaping') they suddenly die.  <How are you modifying your water chemistry? Doesn't sound like predation, parasitism...> Usually their is very little flesh left by this time - my reef hermits will consume what's left within 24 hrs. I suspected the hermits, but they seem to ignore the clams until the very last stage - when its obvious that the clam has died. Also, if I have multiple clams in a tank, they never show illness all at once - its always a one by one demise. I've also tried a variety of positioning of the clams (bottom, middle, top) to no avail. I've suspected a predator, but the shells don't show signs of a boring sponge (or any bore holes from snails). The remaining flesh also appears free of predators. Any ideas what could be causing this - and why my 1 derasa has never shown a day of 'weakness'?  <A tougher species, individual for aquarium use> Are small clams inherently more susceptible to illness? <Yes, more> I also had a few additional questions: - are you familiar with the AquaLogic cyclone titanium drop in chillers?  <Yes, some> If so, are their titanium coils fairly safe (in terms of poisoning tanks)? <Yes> - What is your opinion on the Tunze skimmers and the ETSS skimmers?  <Tunze products are excellent, though pricey. ETSS skimmers are great technology for very large (hundreds of gallons), "messy" systems, in situations where folks don't mind spending the money on high volume pumping. Needle wheel technology is superior to downdraft. My opinions are posted on the www.WetWebMedia.com skimmer sections> The Tunze claims to be completely plankton safe (I've heard the ETSS marketed as plankton friendly).  <Mmm, the Tunze much more so> Are these top notch skimmers?  <Top notch?... for the types of skimmers they are... Tunze particularly for size, cost of operation are very well designed, engineered, built... ETSS are more garage/chop shop put together> Is their 'plankton' spin true, or just marketing? <For Tunze more true> - The ETSS website claims that skimmer throughput (gals of water/hr) is a very good measure of a skimmer's ability. Is this a good measure to compare different brands of skimmers? <No, ridiculous... what does flow rate have to do with removal of unwanted materials. Removal per kilowatt energy consumed, per pass... these are measures of efficiency. Look at the EuroReef line for a paragon of excellence... their link can be found on WWM. Bob Fenner> Thanks!

Clams Hello Bob, I have Derasa, Maxima and Ultra Crocea clams, and they seem to be growing and doing fine. Although I notice there not at all as bright and detailed in color as they were the first few months I owned them. Now the colors aren't that brilliant and they look blurred vs. detailed. What could be the cause of this? I have these clams in a 30g reef with two 36in VHO (one blue, one white) that run nine hours a day, and I replace them every 8 months. Iodine 0.04, Calcium 425, alkalinity 3.5 phosphates low and can never get PH above 7.9, (even using buffers daily PH will rise to the 8's, but fall within 15-20min back to 7.9, 7.8). Any information you can give me is greatly appreciated. Thank you, Rob cook <Hmm, could be a few things contributing to your Tridacnids lack of apparent color/vigor... Most all to do with the small size/inherent instability of your system... Congratulations are due you for your success with a thirty... as you have found out, it's hard to keep stable and optimized... If it were my clam tank, I would do a few things... For one, I'd increase your lighting... you could easily stand to double the intensity you list... best by adding, switching to compact fluorescents... And I encourage you to add a sump/refugium with live rock, macroalgae and its own lighting, leaving it on continuously or alternating the cycle with your main tank...this will do several things for you and your clams... increasing pH, making water chemistry more stable/optimized... provide more food for their filter feeding... Otherwise, I might well add a vitamin, nutriment solution like Micro-Vit or Selcon to the system... and some small fishes to add their bit as well in the way of "processed nutrients". Bob Fenner>

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