It was merely pining!

The fish I thought was dead was, in fact, alive, and is sitting near the bottom of the tank in a totally different position, face up, and everything, so I put a bit of food in. Yay! Not sure about the other one though. The tank is heavily planted and has Java moss and duckweed in it, too, lots of things to hide behind and in, since fish like that sort of thing. But yay!