I would say with the length of that tub, you could probably easily house a 800-900 gram snake in there. Also, I think a 1000 gramer could probably be housed in there too, if you had intentions of getting it out soon. Just my opinion, others may feel that that is pushing it. If they are eating fine and thermoregulating on their own in the tub, I think they are happy. Let them dictate when they are ready to be moved.