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FAQs about Giant Clam Feeding

Related Articles: 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, Tridacnid Health: Pinched Mantle Syndrome in Giant Clams by Dr. David Basti, Deborah Bouchard & Barry Neigut, Bivalves, Mollusks, Lighting Marine Invertebrates

Related FAQs: Tridacnid Identification, Tridacnid Behavior, Tridacnid Selection, Tridacnid Compatibility, Tridacnid Systems, Tridacnid Lighting, Tridacnid Placement, Tridacnid Disease, Tridacnid Reproduction, Tridacnids 1, Tridacnids 2, Tridacnids 3, Tridacnids 4, Tridacnid Clam BusinessBivalves, Bivalves 2, Lighting Marine Invertebrates,

Not entirely photosynthetic

Stony Brook phytoplankton study, and Clam nutr. f'  07/20/2008 Hello crew, Bob et al, Dennis Tagrin sent me this link to a study done on phytoplankton. I do think it's worth reading, adding to the FAQs/other info on phytoplankton feeding. http://somas.stonybrook.edu/~MADL/pubspdf/Emma-clamgrowth.pdf Best, Sara M. <Real good. Will post/share. BobF>

Re: Clams making a fashion statement? Fdg.  - 09/23/07 Hi Bob or whoever reads this :) <Robare back> Thanks so much for the reply! I've turned off the phosphate reactor. They get reef Roids, liquid DFS and zooplankton. Maybe not enough but nothing's changed in the feeding routine and nothing new has been added to the tank in almost a year. <Mmm, not much of these foods are actually filterable by giant clams... I do hope you read where you were referred. Look to appropriate size phytoplankton... soak in supplements of use> I'll keep watching and appreciate the input very much! Thank you, Lisa PS - the link you have posted for the Marine Hitchhiker/Critter ID (Maughmer, Toonen, Tompkins) site is dead. <Thank you... will add to my tasks to ferret out these links... BobF>

Re: Clams making a fashion statement? Fdg.  - 09/23/07 Thanks so much for the response. In my initial reply, I said DFS, it should have read DTs. <Okay> I read the page you sent me to, but I'm more confused than ever. Could you help me decipher please? <Will try> These statements all seem to contradict each other: "<Mmm, my standard spiel on Tridacnid nutrition is that for the most part, all species can be conditioned to do "just fine" on strong lighting, inorganic mineral and some "fish waste" intake... and that addition of exogenous macro-foods... phyto or zooplankter in make-up, are nice, but not really necessary... they WILL enhance color, boost growth under most aquarium circumstances... BUT if folks have refugiums of relative size, vitality... there really is NOT that much difference functionally or aesthetically in what their clams will do> " So I'm reading if I have a refugium of relative size, I don't need to add nutrients? <Mmm, apparently so in this set of circumstances. Your clams are dangerously bleached> I have a 30 gallon sump with refugium. The skimmer resides there as well and I use bio bale as medium which I rotate out every six months or so. "<It is true that these animals do benefit from some dissolved organics in the water column. T. Crocea in my experience is the most light demanding of clams and while it too appreciates "food" it derives most of it's energy from the zooxanthellae within it's mantle. Having said that I wouldn't mess with your system too much, it sounds like it's well balanced and functional. What I might recommend is the addition of phytoplankton, look into reactors if you have the time, effort...as phyto is best fed on a continual drip. If you can't go the reactor route I would at least power the skimmer down or off for an hour or so after feeding the clams.> " So I should add phyto, and power the skimmer down? <I would add more phytoplankton... and put the skimmer on a temporary "off" timer... for a couple of hours> "<Its my belief that they thrive at that small size when they get feedings a couple of times a day>" I should add phyto twice a day? In what quantity? 3 clams, 1 about 4-5", the other two about 2-3". <Mmm, per the bottled ingredients directions...> "<I largely agree. I don't target or bowl feed my clams. If I do feed phytoplankton at all (very rarely), I turn off my skimmer and add the phyto to the main tank. After an hour or so, I turn the skimmer back on.> Any advice on this would be helpful. Thanks, Paul <Glad to help! Best Regards, Adam>" If you feed phytoplankton at all (very rarely)? <For this persons opinion, seemingly so> These seem to run the gamut from don't add anything if you have a good refugium to add phyto twice a day to don't add it at all again. I know it depends on who you ask, but I really need a pat answer. What should I feed, when should I feed it, how often should I feed it, and how much should I feed? <Again... experimentation is all that can tell... It is virtually impossible to overdose. I would mix the feeding aliquot in with a good dose of Selcon... Daily> Eternally grateful, Lisa <Bob Fenner>

Raising nitrates, Feeding Tridacnids...  4/26/07 Dear WetWeb crew, <Hi Joel.>   This is my first time writing to you. <Welcome to the show!> Thanks for all the great information so far. <Thank you for reading.>   I'll keep to the point, my nitrates have been at 0 since cycling 12 months ago. All water parameters are within reef specs.   The tank is a 90 gallon with a 16 gallon sump and 55 gallon refugium.   I have 5 fish, 2 shrimp and about 20 snails & hermits, about 15 inches of fish total. Although everyone is healthy and growing, should I be feeding more or running the Aqua C EV-120 skimmer 12 instead of 24 hours per day? Also, I just tossed out very large ball of macro algae from the refugium called "Fire Algae" which I got free from Inland Aquatics and replaced with small amount of Ulva. <Sounds like a very functional system.>   I want to increase nitrates because I just bought 2 Crocea Clams from Clams Direct and read they and corals need some nitrates. <It is true that these animals do benefit from some dissolved organics in the water column. T. Crocea in my experience is the most light demanding of clams and while it too appreciates "food" it derives most of it's energy from the zooxanthellae within it's mantle.  Having said that I wouldn't mess with your system to much, it sounds like it's well balanced and functional. What I might recommend is the addition of phytoplankton, look into reactors if you have the time, effort...as phyto is best fed on a continual drip. If you can't go the reactor route I would at least power the skimmer down or off for an hour or so after feeding the clams.> Please suggest some ways to safely increase. Thanks, Joel <Adam J.>

Clams and Phytoplankton 11/08/06 Hello Wet Web, <Hello> I have been looking through your site but can't find the answer to my question. How do I know my clam is eating the phytoplankton I give it? <If it is in the water, it's eating it.> I have heard of putting the clam in a bowl with phytoplankton, when the water is clear this means the clam is done feeding. Have you heard of this? Does it work? Most of all, is it safe for the clam? <Yes, No and No!!!> It seems to be opening up pretty well and is very responsive to shadows, color is good. Thanks for the help Mike <If the clam is doing well, then you are caring for it well.  Clams that are small in size (1.5" or less) usually depend more on feeding then the larger ones.  Putting it in a bowl of concentrated phytoplankton will just shock it. Cheers! - Dr. J> Tridacnid nutr.  11/10/06 I got an email back with no reply. Is it something I said? <Mmm... don't see it either... Let's try again> Mike Clams and Phytoplankton 11/08/06 Hello Wet Web, <Miguel> I have been looking through your site but can't find the answer to my question. How do I know my clam is eating the phytoplankton I give it? <Mmm... I guess... w/o killing the animal or doing what is likely an involved assay (radioactive, immunofluorescent labeling or such), just by observing that the animal is alive/healthy> I have heard of putting the clam in a bowl with phytoplankton, when the water is clear this means the clam is done feeding. Have you heard of this? <Mmm... no, or don't recall as such> Does it work? Most of all, is it safe for the clam? <Don't think so on either count> It seems to be opening up pretty well and is very responsive to shadows, color is good. Thanks for the help Mike <A bunch to state, but is already written/archived here: http://wetwebmedia.com/tridacfdgfaqs.htm and http://wetwebmedia.com/BookMatters/WWM/NMA-RI/NMA-RI_Tridacnids-demo.pdf and the linked files above. Bob Fenner> Clams, lights, Feedings - 7/31/05 Hi <Hi Steve, Ali here...> I was reading you site about T. Clams and got mixed information about lighting and feeding T. Clams. Here's my question can an adult T. Maxima survive and thrive in a 60 aquarium with 260 watts of PC lighting. <That won't cut it Steve, you need halides, preferably 2 x 250watt bulbs. P.C. just aren't intense enough to keep the clam happy long-term.> My second question is do T. Clams over 5 inches still need to be feed live phytoplankton, My last is question will a T. Clam eat copepods and such. <No and no. Intense lighting along with stable (moderate-high) calcium/alk. parameters will be enough to keep him healthy and growing> Sorry about all the questions but I really want one but don't want it to die a few days later. Thanks <Good luck and keep reading Steve! - Ali>

Re: Tridacnid book matters Thanks Bob, FYI - As far as Brian Scott mentioning a revision by Knop goes - I questioned him on it and have gotten no response after several days.  Maybe BS - wouldn't be the first time... <Mmm, and I did mention your mention to BarryN... he recollected chatting with DanielK at the Boston MACNA a few months back and hearing from him that he'd welcome help in revising his book... so, I know naught.. 'Cept that if all three books were to come out, be revised at about the same time, ALL three would sell all the rest... am not joshing here.> I'm currently sorting through a handful of refs on nutrition this weekend - and I am getting more and more perturbed as I turn each page - as they directly contradict what has been said by some re feeding. Shimek has written an article on subject for DTs and then used a few refs to back up his claim that ALL clams will die if you don't feed them.  So I got the refs myself - and they say just the opposite for the most part.  One of them doesn't even have the word "feeding" anywhere in it - yet he claims that the same paper shows that clams must feed.... <Mmm, my standard spiel on Tridacnid nutrition is that for the most part, all species can be conditioned to do "just fine" on strong lighting, inorganic mineral and some "fish waste" intake... and that addition of exogenous macro-foods... phyto or zooplankter in make-up, are nice, but not really necessary... they WILL enhance color, boost growth under most aquarium circumstances... BUT if folks have refugiums of relative size, vitality... there really is NOT that much difference functionally or aesthetically in what their clams will do> On the same subject, I also have some very interesting stuff showing that Mytilus not only eats phyto and zoo, but grows faster when given a mixed diet of both... Quite a few other bivalves eat zoo, too. No, they're not Tridacnids, but interesting to say the least as it is generally thought that bivalves eat only phyto of a certain size, density, etc. <Mytilid culture is VERY important in parts of the world. I have some pix (somewhere) of back in the early seventies off of Spain with many MANY hectares of their culture.> Still reading... Adios, J <You go James. Bob F, who just finished copying the Dec. ish of TFH incl. your cirrhitid piece.> > James, Barry and I were visiting, chatting yesterday > (please see his new > email addy above), and we bantered back and again re > Knop, books... he said > he has a bunch of reference material that you may > not have... and would > gladly offer same to you... so am writing re. And > will get on to the list > you sent. Bob F

Re: Tridacnid book, feeding matters Date: Sun, 9 Jan 2005 22:41:04 -0800 James, Like you, have read so many different things regarding feeding or not feeding Tridacnids so decided to do some research ourselves and see what results could be found. Set up two 15 gallon tanks and placed 15 juvenile clams (1.5") in each tank, lights being equal and water chemistry being equal. Adding food supplement to tank A, and no supplement to tank B.  After 6 months we still had 11 clams alive in tank A and in tank B we had 5 survive. Not taking into consideration that the health of each specimen may not have been equal. :) I have also done some feeding with different food supplements such as DT's, KoralVitF, Liquid Life and Marine Snow.  With adult clams we have found out that they seem to do fine without supplemental feeding. Zooxanthellae were indeed believed to provide a significant portion of the clam nutrients that filter feeding did play an important role in the prolonged survival. ( Reid et al. 1984)  I also agree with his assessment. With that being said, I would also agree that if an aquarist has a sufficient bio-load in his/her aquarium then there might be enough food particles and other nutrients as well as fish waste to provide the Tridacnid the necessary supplement food as well as symbiotic algae. Would I tell a newbie that he doesn't have to feed his Tridacnids, no. It certainly would not hurt and not that expenses if MAYBE it did help in keeping them alive. :) James, as Bob and Anthony knows, I could go on and on regarding this topic and the debate continues. :) Will we ever REALLY know and understand the Tridacnid to the fullest? Also, have done some testing with salinity and pH swings as well with keeping Tridacnids. Regards, Barry <Thank you for this Barry. BobF>

FEEDING CLAM Hi all. <Hi Cord, how's life?> Thanks for such a great informative site. I have a question regarding feeding my 3-4 inch tridacnid clam that I have had for about a year. He looks great and seems to be doing quite well. <Sounds like you are doing wonderfully with it.> I feed DT phytoplankton, usually an hour or 2 before lights out. Is this the best time to feed clams, or do they eat better in the dark, daytime, or does it not matter. <Its my belief that they thrive at that small size when they get feedings a couple of times a day. The expert on clams is Daniel Knop, and if you haven't purchased his book I can highly recommend it. I also suggest that you take a look at the articles on wetwebmedia about clams and especially the FAQs. You might start here, http://www.wetwebmedia.com/tridacnidart.htm  > I notice at night the mantle isn't extended, so I'm not sure if they stop feeding too. Thank you for your advice and keep up the great work.  Cord. <Thank you so much Cord. I think you will find lots of information about clams on the website if you start there and just go to all the sections about clams. You are on the right path by asking questions. MacL>

Clam Feeding 4/14/04 Hi,  I have decided to try clams after a year and a half, but I am really confused about something.  I have gotten and heard advice on how to feed them.  I have been told that you need to really work at feeding them directly.  Not only that, but it isn't good enough to feed them something like DT's, now you have to run it through a blender to break it down even more...you need to shut off powerheads and using a syringe, inject the blended DT's all around the clam and let it sit...OR...better yet, put the clams in a bowl of your reef water and put the DT's in there and let it sit for 15 minutes or so.   <Hmmm..  You must be hanging around the message boards!  So many differing opinions and everyone so convinced they are right!  Phytoplankton products are available that are spray dried.  These products tend to clump and may require action as drastic as the blender to get them down to their original size.  Spray dried products have very poor food value and should be avoided anyway.  DT's is fresh live phytoplankton and can be used as is.  It can be added to the main tank, which would be my preferred method since it will feed other critters besides the clams.  Some folks do suggest placing the clam in a bowl for feeding.  This is fine, just be careful not to add to much phyto.  The clam can be returned to the tank when the water in the bowl turns clear, indicating that all of the phyto has been consumed.> My confusion comes, because I have read that clams are very good water filters.  They will filter your water and can actually improve water quality even more. <Clams (especially large ones) are amazing consumers of nitrate and ammonia.  In fact, clam farms drip ammonium nitrate into their grow out systems as clam food!  Just don't try this at home!> If they filter water so well, and I am diligent about adding good supplements to the water and keeping the water quality good, won't they get the food they need from the "natural" way? <No, they won't.  Supplements aren't food.  Clams feed on very tiny plankton (phytoplankton and maybe some of the tiniest microscopic zooplankton) as well as direct absorption of some organics and nitrate and ammonia.  Our tanks are very low in tiny plankton for many reasons, so adding it is the only way for the clams to get it.  As an aside...  Be very careful in choosing and using supplements.  Most are easily over dosed.  Calcium and alkalinity are the only things that must be supplemented.  The golden rule is not to add anything that you don't test for.> It seems to me that always messing with these clams to make sure they are fed "properly" would be more irritating and harmful in the long run than providing them a good environment and letting them eat the way God made them to. <I largely agree.  I don't target or bowl feed my clams.  If I do feed phytoplankton at all (very rarely), I turn off my skimmer and add the phyto to the main tank.  After an hour or so, I turn the skimmer back on.> Any advice on this would be helpful. Thanks, Paul <Glad to help!  Best Regards, Adam>

Re: Clam Feeding 4/26/04  Adam, Thanks a lot for the response. I really appreciate the time you took to provide good answers. I ask a lot of questions, and it seems like I get blown off a lot of times with incomplete or worthless answers.  <It is always a pleasure! Sorry for my slow follow up. I was out of town putting the final touches on the forthcoming "Conscientious Aquarist" magazine. Look for it on May 1st!>  You got my interest up when you talked about feeding the tank. It sounds like you don't even do too much of the DT's feeding of your tank.  <I do some. Also, FWIW, Liquid Life makes an excellent concentrated phytoplankton product called "bio-plankton". I use this more often than DT's because it is much more cost effective.>  When I talked about supplements, let me clarify. I use B-Ionic every day. Once a week, Monday nights, I add four drops of Lugol's Solution.  <B-Ionic is an excellent product that contains a variety of trace elements, including iodine. Lugol's is very concentrated, and at very least you should be testing your iodine levels carefully while using it. Overdose with Lugol's is very easy to do.>  Every other day, I add some kind of filter food: Monday-Marine Deluxe, Wednesday-Marine Snow, Friday-DT's. I do nothing on Sunday, B-Ionic or otherwise, day of rest :-)...only thing I do is feed the fish. That's all I do. Does this sound okay, or am I doing too much?  <Sounds fine. I don't know much about Marine Deluxe, but you can get your own marine snow for free by stirring up detritus. Packaged filter feeder foods generally don't provide a lot of food value. Good quality live phytoplankton is the exception (DT's and Liquid Life).>  Thanks again, Paul  <Thank you for the kind words! Adam>

Yeast and filter feeders 2/29/04 I have read that Knop recommends using yeast to feed Clams and various filter feeding corals. <limited applications (species that will/can eat it) but very effective for those few. Like many nutritive substances added to the tank, it can be easily abused and feed nuisance organisms growths just as easily> I have been unable to find good instructions in creating/using a yeast drip, can you give my some instructions?. <I am not aware of any specific protocol.. just judicious experimentation like using iodine, phytoplankton, etc where small amounts are added until a slight response in nuisance algae like diatoms flares, then back down to a previous dose and ride for a while> I am extremely interested in this method to help supplement food for filter feeders. <interesting but very limited as its particle size is so large. Do resist this feeding style in any lg qty> Also, could a drip help increase the rotifers etc... in my refugiums. <they would benefit much more by a phytoplankton drip> What are its disadvantages/advantages to phytoplankton use? <if live, they will feed some bivalves, microcrustaceans and s few corals. Still... zooplankton is a much more important food to provide> Finally, I know some people include yeast in there coral ration home made mixes that they make and freeze, how effective is this. <no idea... I've never seen a study on it, but if one exists it would be in fisheries data... do explore there my friend> Thank you Greg <Anthony>

Feeding Corals and Clams Ammonium Anthony- What sort of regimen would you advise I use if I began using ammonium chloride?   <I personally like using nitrate better... no idea of ammonium is better though> Is there any ay to test the level present in the tank? <not as easy as nitrate <G>.> Darrell <Anthony>

Feeding Corals and clams that feed by absorption Nitrate solution????  Something like Barium Nitrate?   <sodium nitrate actually, bud. And done so in aquariums with limited (or zero) nitrate. Yes... nitrate is bad if excessive... but zero is bad too. Many of our reef invertebrates need a direct source of nitrogen> Again, what would the regimen be? <p 323 of the Book of Coral Propagation says <G> Heehee... [just shameless]: citing Knop...1 gram of sodium nitrate per 1000ml distilled water to make a stock solution. From the stock solution, dose 10ml per 100 L of aquarium water incrementally to maintain a nitrate level under 2 mg/L >



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