golden clams look bad

I have some ~ ph 7.4 and I don't know about the hardness ~ zero nitrates, nitrites and ammonia.

Are these the golden clams from AZGardens, aka Asian clams? If so, they do need to be fed despite what AZGardens' website says. But they shouldn't be doing what you're describing after just a few weeks ~ it should take months for them to starve. I'm still wondering if the really are starving, not because YOU did it but because they weren't fed at all for a looooong time before you got them (if you got them from AZGardens, then it wouldn't be surprising that they didn't feed them, given what they say on their site). Unless your aquarium water is green a lot of the time (as in green water, the type of algae that's suspended in the water, not the kind that clings and grows ON things), there simply isn't enough food in there for them.

I've been feeding mine Kent Marine Micro-Vert filter feeder food for three or four months now and they seem to take it fine and are healthy from what I can tell. Green water is another good food source, but can be a pita to culture if you don't have the room. I keep my clams in a small pot with substrate in it so I can move them from tank to tank and into a smaller tank when I want to feed them a lot and don't want to cloud the main tank's water (about once or twice a month).

I'd take them out of your tank and put them in some clean water of their own, even in a big bowl or jar if you have to. That'll make it easier to watch them and see whether they're eating or not. Retracting their siphons doesn't sound good ~ they might not eat at all now. But it wouldn't hurt to try feeding them. I'd do that ~ put them in a separate container and feed them (OVERfeed them even, making the water cloudy enough you can barely see four inches into it), doing water changes every few days to make sure the water is clear of any excess, rotting food. I'd check each one every time you change the water, making sure they're all still alive. A dead one can foul the water and affect the other ones.

Don't get too worried if you don't see the water clearing very fast. Mine came from my creek so were very healthy when I first got them, and a dozen of them cleared about three gallons of slightly green water in a couple days. But I've seen them take longer than that to clear a similar amount of water, probably because they weren't so hungry after that.

What are your water parameters? Everyone's right that they're touchy when it comes to ammonia. I haven't had mine long (less than six months), so I don't know a LOT about them from experience, but have read extensively (atleast as extensively as what's on the 'net, which isn't a whole lot regarding keeping them in an aquarium). What I've read leads me to believe they like similar conditions to cherry and ghost shrimp.

Are you using any dechlor? If so, what kind? Some kinds can kill shrimp, so I'd think those kinds aren't really good for clams either. There's a kind that's safe for shrimp and I'd suggest you using that same kind. Not sure which it is ~ I'll go start a thread in the shrimp forum asking about it.