I wonder if you could mount the camera up high in the vivarium, about a third of the way down the length of the enclosure...then point it towards the closer end and have a mirror mounted there...so aiming the camera at a mirror. That might increase the field of vision significantly. You could use the camera settings to permanent flip/rotate the image as needed. That might also reduce the chances of something crawling on the camera and peeing in it or getting dirt on the lens. You might experiment with a USB webcam that has a similar lens and see what kind of results you can expect, but keep in mind that the IP camera is going to be significantly bigger than a USB camera...meaning the lens will be further from the walls/ceilings of the container than that of the webcam. If the viewing field isn't wide enough, you might need the wide-angle lens (just make sure it won't interfere with the IR). Also, some cameras do well with IR, but do not have realistic colors for visible light...so make sure you read plenty of reviews before purchasing the camera. Also consider the temperature and humidity inside the vivarium where the camera will be located.
P.S. Now that I think about it, doesn't this camera have PTZ? If so, I guess you wouldn't need the wide-angle lens...you could just rotate the camera.
