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Im reprinting this from another thread because I think it will reach a larger audience here.....
I'll offer my two scutes on this to feed or not to feed debate.
I talk with three major Tridacna clam farmers often .
None of them feed their farm clams with any form of supplemental plankton.
They all do however, when they want to get them to grow faster ...feed with nitrogen/ammonia fertilizer pellets.
But they understand that they are actually feeding the tiny zooxanthella inside the clams , more so then the clams themselves.
They also don't suggest hobbyists feed clams in their aquarium anything other then ammonia in the form of fish waste.
There are many studies comparing clam growth with and without fish in the system. Fishless systems always yield slower growth.
It's the constant supply of ammonia feeding the zooxanthella which is important.
I have studied clams for a few years now; under the microscope, one can clearly witness the zooxanthella inside a clam's blood stream and stomach along with amoebsites which farm the zooxanthella, a little bacteria and not much else.....
But oddly enough , I have never found plankton?[neither zoo plankton or phytoplankton] EVEN after days of target feeding.
It seems that when fed, clams do filter out plankton from the water and it can be found concentrated on their gills. But with filter feeders, they filter every thing in the water, so the plankton gets stuck to their gills just like every thing else in the aquarium water.
[ Just like filter floss would stain out indiscriminately ]
Just because the clam filters the water , does not mean the clam is eating the plankton.
In order to be eaten , the clam must ingest the plankton.
Ingesting food is carried out when the clams gills allow only certain substances to pass through their membranes. Kinda like a reverse osmosis filter.
Most of what a tridacna clam filters with its gills is ultimately pooped out or coughed up before it ever gets into the clams digestive system.
Clams dont even let non motile zooxanthella past their gills.
Preferring zooxanthella with tails. It is thought that its the swimming action of the zoos tails that triggers the opening of the gates so to speak and into its stomach.
Some feel that yes, clams do seem to have the appropriate mouth parts to feed and therefor nature would not of designed them with such mouth parts for feeding if they did not intend to make use these feeding abilities.....
BUT! One could ague that the sole use for this feeding ability is to take in Zooxanthella .
Afterall, without his ability to feed on Zooxanthella , baby clams would die . Baby clams are not born with zooxanthella inside their body.
Giant clams may simply use this feeding ability as a way to inoculate themselves with zooxanthella.
As humans, we have several uder utilized organs, such as our tonsils, appendix and for many of us , our "better judgement"
Furthermore, There are reports of clams choking on too much plankton paste and it clogging their gills and clams dying from too much of a good thing in over fed, low pH,nutrient rich aquariums.from overfeeding. Contrary to a misconception, clams dont like high Nitrate levels.
I at times wonder if the bad rap small calms get for being difficult to raise, comes more from hobbyists killing small clams by over feeding the tank resulting in high nitrates,a lowered pH, and otherwise less then ideal tank conditions. ........then these young clams would do if just treated like any other coral or anemone, with proper water conditions and a well cycled tank?
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