filter causing fish to jerk

Question
I'm new to this and I'm setting up a 10 gallon aquarium.  While trying to get the bio of the water right, I just have one comet in the tank.  I noticed the comet is hovering near the bottom and jerking (or perhaps quivering is more accurate) and looking distressed.  I unplugged the filter and the behavior becomes normal again.  Repeated several times.  The tank and filter are new and I am perplexed as to the cause.  Don't want to add any more fish until I get this figured out.

Answer
Linda,

 If I am right, you are cycling the tank with a fish, correct? If so, it is better to cycle without fish in the tank. Your first bacteria bloom, that happens within the first week, has bacteria that is harmful for the fish. After that bloom there will be another one, a week or so later, this bloom has the beneficial bacteria that the tank needs. As for the strange behavior of the fish with the filter, the only thing I can think of is there is a short in the filter. The fish is getting electric shocks and that would explain the "quivering" while it is plugged in and not when unplugged. I would get a different filter and try that and see if the fish still behaves that way.