Thank you all so much! I lied about that being my last question.
So I have the new tank all set up. Water's been conditioned, plants planted, filter started. As a result of the old tank being overstocked and overplanted, it's disgusting. And at this point I don't know which is worse: to put them in the new tank so soon or to let them spend a night with crap and whatever else was under the plants in their old tank?
Should I switch them over early or hope they survive their filthy tank for the night?