WARM CORNER

This is making a warm place in the tank or cage to allow an animal to choose to stay warm or not. For an aquarium you can either shine a gooseneck or swingarm light at a corner of the tank, about 3-4 inches (8-10 cm) away and a few inches above (5cm or so) the line of the bedding. Put an adhesive aquarium strip thermometer on the outside of the tank to make sure the temperature inside doesn't go over 85F(about 29C). If it's a cage, do similar, aim the light at a corner, but make sure the animal(s) inside can't get to the light or kick bedding on it. If you have an aquarium you can also put a small adhesive reptile heater on the outside bottom of the tank at a corner instead of using a light. You have to be very careful not to get the heater wet though, and it can be hard to do that when you clean the aquarium. And those heaters are expensive.

This is good for if you are worried about the temperature of the room you have your gerbils in (like your furnace went out) or have a mother with pups or are treating with ornacycline for a respiratory problem or have an animal you are treating for something else.

Use a 40 or 60 watt incandesent bulb. Fluorescent will not work (those energy saver or greenbulbs that have the white ceramic base and the white tubes) and neither will those high intensity SN11 small base clear bulbs, and neither will halogens of any kind. Halogens get extremely hot and are too hazardous to use for this.