can find someone who has a really big reef
tank. For anyone that does have a really
big tank, none of this really matters, and in
fact their eventual size can be considered
another pro, rather than a con.
The only other con that I can come
up with is their ability to rapidly deplete
calcium in an aquarium. You won’t notice
anything unusual if you put a relatively
small specimen in a relatively large tank,
but you very likely will if you put a larger
derasa in a small- to medium-size tank.
They take calcium from the water in
order to add on new shell material, and
you have to remember that they make a
thick shell. When a derasa adds on shell
material, it doesn’t just make it longer
and taller, it also adds on a significant
amount of material to the inside of its
shell, too. It gets thicker and thicker all
the time. So you’ll need to keep an eye on
the calcium levels in your tank if you buy
a derasa (or a gigas, for that matter), and
make sure that you keep things within an
The nutritional value of the popular
phytoplankton products were recently tested
by 2 feeding trials on juvenile hard clams,
Mercenaria mercenaria. The results were
published in the November/December 2006
issue of the peer review journal Zoo Biology.
A big T. derasa can certainly be an impressive
sight in a reef aquarium.
The products tested included; both
powdered and liquid products stored at room
temperature, the popular frozen concentrate,
DT’s® Live Marine Phytoplankton, A product
marketed as being a refrigerated live
phytoplankton but with more species than
DT’s, and a product by the same company
that is advertised as having the same
nutritional profile as live phytoplankton.
An Educated Decision
That’s about it. As you can see, the pros
greatly outweigh the cons, so if you are
in the market for a giant clam, put some
thought into what I’ve presented here, and
make an educated decision.
“The commercial blend,
DT's® Live Marine Phytoplankton
seems to represent a good
substitute to lab grown algae
for clams held in ornamental
or experimental aquariums.”
DT’s® Live Marine Phytoplankton was the
only product tested that was effective in
growing juvenile clams.
Zoo Biol 25:513-525, 2006. © 2006
The results from all of the other products
tested were consistent with not feeding
the clams at all.
Adams, T. J. H., A. D. Lewis, and E. Ledua.
1988. “Natural population dynamics
of Tridacna derasa in relation to reef
reseeding and mariculture.” In: Copeland,
J. W. and J. S. Lucas (eds.) Giant Clams in
Asia and the Pacific. ACIAR Monograph
Number 9, Canberra. 274 pp.
Crawford, C. and W. Nash. 1986. “Giant
clams.” Oceanus 29: 60–61.
Fatherree, J. W. 2006. Giant Clams in the
Sea and the Aquarium. Liquid Medium.
Tampa, FL. 227 pp.
Lewis, A. D., T. J. H. Adams, and E.
Ledua. 1988. “Fiji’s giant clam stocks—A
review of their distribution, abundance,
exploitation and management.” In:
Copeland, J. W. and J. S. Lucas (eds.)
Giant Clams in Asia and the Pacific.
ACIAR Monograph Number 9, Canberra.