something is fishy here
LOL
all does sound like a fw aquarium, and this is a saltwater board, but funn isn't it, all of us must love fish becasuse we are all checking in to help
anyhow, if one disappeared, mysteriously, i'd look all around the aquarium stand, he may have jumped out, but the other one, ????,
as for your water parameters, they are your test results, have your local fish store run some tests on your tank water, there could be a problem there, othe than that, i really don;t know enough to help you much, unless your filter and airation aren't workin properly