Just curious, what is the temperature range your tanks are at, max, min, and what resolution are you looking to achieve.
For temperature alone, I've done a project with a few students using thermochromic liquid crystal sheets and a digital camera. FYI, a thermochromic liquid crystal sheet changes color at different temperature so you can attach a patch on every tank and just use one camera to get everything in one shot and keep grabbing frames. All depends on how accurately you want and the range of temp.