I have a small tank with 4 guppies in it and one of the guppies spends most of its time on the bottom of the tank, it hardly comes up and swims around with the other guppies. The tank has a filter etc, have checked the PH level and the temperature and all is OK there. Is there something else I should be doing?
It could be female and super pregnant, or it could be dying. Does it eat? Does it poop? If it does, and it does not have any visible signs of parasite or fungus, then it is likely healthy. Is it smaller than the rest? Does it hide or does it just prefer to swim at a lower level than the rest? Do you ever see it interacting with the others? Do the others attack it?
Several things come to mind. First of all, you said "small" tank. How small? Four guppies should really have a ten gallon tank. If you have less, the weakest one may be suffering.
Secondly, how old is the guppy on the bottom? Is it possible to be an elderly guppy with no energy?
The Ph and temp is fine, but what about ammonia and nitrate? Have you checked those and metal content as well.
References :
It could be female and super pregnant, or it could be dying. Does it eat? Does it poop? If it does, and it does not have any visible signs of parasite or fungus, then it is likely healthy. Is it smaller than the rest? Does it hide or does it just prefer to swim at a lower level than the rest? Do you ever see it interacting with the others? Do the others attack it?
References :