We used a 10 gal tank with a screen lid. half the lid was covered with a piece of plexi and then we used some black fabric over that. we had heat tape under the tank and a 60 watt bulb for the daytime. we kept a therm in there at all times and checked the temps daily to make sure that it stayed in the 90 degree range.
and yeah, the bubbles and mucus in the mouth is another sign. kind of like this...http://www.exoticpetvet.com/breeds/S...%201%20web.jpg