Seamay - I think at this point you can place your clam wherever you think it will be safest and thrive. I think it is fair to say that we have established that your clam will be fine up in the rocks, or down on the bottom of your tank. If the goby is a problem, and there is a safe spot for the clam in the rocks, this may be your best bet for now.
mbbuna - Thanks for the clarification. As I suspected, my confusion that resulted from your post was due to misinterpretation. I fully agree that clams in the wild do not commonly live in a sand bed such as we normally have in our tanks. My point was that gigas and derasas live on the bottom, as opposed to the reef structure (being corals, live and dead), which I now see that you agree with. I think this brings up a point that reef keepers commonly overlook, as I just did. In our tanks, "bottom" most often equals sand. On the pacific reefs, "bottom" does not usually equal sand. This is where my misinterpretation was. Anyway, I do agree with you about the sand. Personally, i still like to keep derasas on the bottom of my tank, but I put a flat piece of rock under them buried slightly under the sand for them to attach to. Hopefully this more closely simulates the normal conditions they live in. In reference to your pictures, I am glad to see such healthy wild gigas. Obviously, I had no idea where these pictures were from, which is why I was so curious. My only personal experience with a clam mariculture facility was in Kosrae, F.S.M. They kept their gigas and derasa broodstock in about 30-50 feet of water, in different locations around the island. They were kept in close groupings, which your picture reminded me of. These groupings are pronounced, and their locations are well known, so that locals can easily recognize these clams as broodstock and not take them for food. This was part of the reason why I thought your pictures might be of broodstock clams. The two together not only looks unnatural to me (from an ecology/evolution point of view), but also presents a target that would be twice as easy to find as a single gigas would be for anyone looking for clams as food. The second picture shows how shallow the clam is, also making for an easy access meal. That made me think that they might have been protected broodstock. Anyway, it was all just speculation, as I have no idea where these came from. Maybe they are nowhere near an inhabited island. Anyway, thanks for all the information, it's always nice to hear a little more about these wonderful clams.
