water qualities all good. i have a trio in there. one of the females sometimes breathes fast. the tank has oxygen so that's not a problem. oh and shes got really bllack eyes. and she shakes abit if thats how you describe it
guppies usually sit on the gravel. Mine do it and I've heard of other people who have experienced this. It's sort of like they're sleeping. Turn on the lights and in a coule of minutes they'll start swimming around again.