I have a fish that seems to be lazy lately. He sits on the bottom of the
tank, just staring around, unless he thinks it's time to be fed, and then
he's very active and swimming.

No problems with water parameters (good PH, no ammonia or nitrites), good
temp, etc. The other 3 fish (4 fish in a 40 gallon tank) are all fine. The
fish in question looks healthy, just lazy. It's been going on for a few
days.

Any ideas?

Thanks,

Devin