When the snake goes under the dish it and coils up they actually do tilt the whole dish to one side or the other. Again I have the same exact thing. I'm not talking about tipping the dish from the top. I think you are worrying about spilled water.

A bath should be in your bathtub and you should use warm water and cold water with a thermometer in the tub and adjust the water temperatures until the water is 88.f. Do you have a digital thermometer around? Stick that in the water. I have no idea what you were talking about with the fish heater but that's not going to work.

Personally I think the more you worry about this guy and think somethings going on with him, you could actually create a problem. This is all normal, do the bath but after let him be.

K.I.S= keep it simple!!! Your over thinking!