Sick guppies

Question
We have a tank full of guppies.  Lately we discovered that we have been losing about 1 or 2 guppies a day without any apparent skin ailments, etc.  The only symptoms we can determine is that several fish per day are hanging out near the bottom moving very lethargicly or almost no movement at all resting on the bottom.  Most of the other fish are hanging out near the top of the tank.  Water is clear with no odor.  Aeriation seems ok but we do not run a airstone.  The one's hanging on the bottom seem to be the one's dying as the get progressively less active.  No floaters, all on the bottom.

Can anyone give me some ideas on what we may be dealing with and what we can do to isolate and/or treat the problem.

Answer
Ok well you might have an ammonia or nitrite problem if those are high they could kill your fish. If you don't have a test kit for ammonia, nitrate, nitrite, P.h., alkalinity, and hardness you need to get one. Is your tank filtered? What size is your tank? is your tank heated? How many guppies do you have? If i were you i would start looking for diseases white dots, clamped fins, rotting fins, parasites (worms), and other unsual things.

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