What Colour of curtains suitable for aqua blue walls?

Any color in the blue or green family would work with aqua green walls, generally deep colors for contrast. Brown is another alternative, depending on your personal preference, even a burnt orange...

If you wall is blue, you could use another shade of blue such as a royal blue or a contrasting color such as an olive green. It all depends upon the shade of blue that you are trying to match and...

I'd say a cream colored carpet with sky blue walls.

white brown or tan

both