Ball Python in 40 gallon long tank?/Gerbils and snake in same room?

[Malum Argenteum]

Personally, I think fish tanks of any size are the worst choice for most snakes, including ball pythons. They're used because they're widely available, and people often have one lying around, but neither of these considerations matter to the snake.

Tubs in enclosed rack systems in a room with appropriate ambient temps can indeed work. People do rig up stand-alone tubs; I think those setups are sub-standard in a few ways. I think that saving money on an animal enclosure is a financial mistake, as one vet episode precipitated by substandard housing can exceed the cost of a very nice enclosure (to say nothing about the non-monetary value of the animal's health itself).

I personally think the commonly used tub size used in racks (CB-70) is too small for a ball python. I keep many snakes in tubs, but my male BP in that size tub just wasn't acceptable in my opinion. I do have experience keeping snakes in larger tubs (Sterilite Tree Box), but fighting with such a big tub gets old quickly, and heating that space is a real challenge (minimizing challenges is best; there will be challenges enough anyway).

A far, far better enclosure in every way is a PVC display enclosure heated with an RHP. I think an AP T8 is OK for an adult BP, though some keepers would recommend a taller (or larger) model and I would not argue with that.

I raise mice (and in the past, rats) in the same room and in close proximity to my snakes and have never thought there were any problems with that arrangement. Some snakes may react to the scent of rodents on a keeper's hands with a feeding strike, so washing hands after handing rodents is a good idea (regardless of whether one owns snakes or not, but in this situation there's an extra reason).