VHO's & Derasa clam

[crumptondan]

Hello everyone,

I'm new here, actually my first forum chat ever!
Anyway, I have a 55 gall. reef/fish tank (Established 2+ yrs.)
with 2 VHO's (50/50 10,00k, super actinic-both 110w)and T-5 actinic retrofit
for sunset and sunrise.
I also have about 100 lbs. of live rock, two emporor 400's hang on back filters
and super skimmer.
Inhabitants:
2 cleaner shrimp, 1 yellow tang, 1 coral beauty, 2 saddlebacks, 1 dottie back,
3 clowns, star polyps, frog spawn, fiji leather, shrooms, candy cane, BTA, 2 sand conchs, 4 red legged hermits, 6 bumblebee snails, and a partridge and a pear tree.

I do water water changes religiously every two weeks with distilled water
and instant ocean. supplement tank with tech CB A & B, Iodine, and trace elements. I feed ISO flake food for fish and cyclopeze along with D.T's phytoplankton for corals.

Now, that I've got all that out I just recently added a small derasa clam(aapox.2.5"-3" across) is the outlined above acceptable enviroment for maintaining the health of this guy?

[Ninong]

I just recently added a small derasa clam(aapox.2.5"-3" across) is the outlined above acceptable enviroment for maintaining the health of this guy?

Yes.

[crumptondan]

Thanks for feed back, everything I've been reading would lead someone to think VHO's
are no good for the zooanthalae in the clam's mantle.

[Ninong]

Points to consider:

• You asked if your lighting is adequate for your baby derasa clam. The answer is yes.

• Assuming you have a standard glass 55-gal aquarium, then it is only 20" tall, including the bottom glass. Your water column is not much more than 18" high and that's before subtracting for a sand bed, which is something that is VERY good to have.

• The only thing that really matters is the intensity of the light incident on the clam's mantle. We're talking about PAR (photosynthetically active radiation) measured in PPFD (photosynthetic photon flux density) units.

• Of all the tridacnids, dereasa clams are the least demanding when it comes to light. Crocea clams require the most light, followed by maxima clams. Both of those clams are called boring clams because they bore into hard substrate (live rock or even live corals). Derasa clams lose their byssal attachment to the rock or other hard substrate after they mature and water currents eventually cause them to land on the sand bed.

• For crocea clams, and even maxima clams, metal halides are best but HO T5s and even VHOs will work for these clams if the clams are located appropriately high on the live rock.

• You have a baby derasa clam. Right now it is getting approximately 60% of its nutrition from photosynthesis and 40% from filtering. After it matures, it will get about 90-95% of its nutrition from photosynthesis and only about 5-10% from filtering. Right now it would be a VERY good idea to add some live phytoplankton to your aquarium daily. I like DT's live phytoplankton. (P.S. -- Those percentages refer to natural conditions. So if someone reading this wants to tell me that they never feed phytoplankton to their aquarium and their tridacnid is doing fine on photosynthesis alone, then that's what is has to do to adapt to the unnatural environment it finds itself in. Survival rates for baby tridacnids in aquaculture are much better when they are fed. It is also quite likely that a mature, fully-stocked reef aquarium produces enough nutrition to support tridacnids without supplemental feeding of live phytoplankton. However, feeding live phytoplankton is still a VERY good idea, especially when it comes to baby tridacnids.)

• I assume that you are keeping the 54w HO T5 actinic lamp on with the VHOs, having it come on before they do and go off after they go off.

• Your derasa clam should not be placed too far to either end of the tank or too far to the front glass. It should be placed where it will get the best light. It does not have to be placed on the live rock. These clams should be placed on the sand bed unless the aquarist has a real problem with light and needs to place it high on the live rock temporarily before upgrading the lighting. Your present lighting is adequate for a derasa clam on the sand bed.

Good luck!



P.S. -- This is a fast-growing clam that will get pretty big in no time at all. That will be your excuse to upgrade to a larger tank four or five years from now.

[Steve McKay]

In time I will acquire a derasa too.This info was quite helpful.Thanks Ninong.

[Ninong]

One thing you guys have to remember is that even though the derasa clam is probably the easiest of the tridacnids to care for it is also one of the fastest growing and it can get quite large in a hurry. This has to be considered in advance when setting up a place for it in the aquarium, especially if the aquarium doesn't have very much front-to-rear space.

A 3" derasa clam should be 6" in a year if it's in a healthy environment. Their growth slows down as they mature but in their natural environment they can reach 20". In a healthy reef aquarium, they should reach 8-9" in three years if they were 3" when first acquired. They could easily reach 12" in less than five years.

That means that you have to allow for this anticipated growth when you make a space for them in your tank. You don't want their mantle to be shaded by overhanging corals or live rock.

My doctor set up a beautiful 210-gal reef tank in the lobby of his office building about two years ago. He put in a beautiful little gigas clam that was about 5-6". Right now it's about 12" and he's going to have to rearrange the live rock around it because the spot it's in now has no more room for it to grow. Both gigas clams and derasa clams are fast growers. They grow much faster than crocea or maxima clams.

[Steve McKay]

Ninong,how much sand can a derasa tolerate.I have a sand throwing goby and was wondering if he would pose a problem.

[Ninong]

Also remember that clams do not like strong water currents. This is usually not a problem with derasa clams because they should be placed on the sand bed and that's usually the best place in the aquarium for them when it comes to water current.

The problem of keeping clams away from strong water current is usually something that comes in play when trying to find a good spot for a crocea clam or maxima clam.

[Ninong]

Ninong,how much sand can a derasa tolerate.I have a sand throwing goby and was wondering if he would pose a problem.

Well, let's look at it this way, they can usually survive quite well in the ocean where there is quite a bit of turbulence caused by strong waves resulting from tropical storms and other natural conditions. On the other hand, I would try to avoid placing anything where it's going to be constantly buried in sand from an annoying goby. That applies to corals as well as clams. You're going to have to use your own judgment.

[Steve McKay]

Ok,now that I think about it.That was a dumb question,I just didn't think about it in those terms.Of course I wouldn't place it near one of his dens either.Thanks.