Well, I'm not a paint expert, I have no idea, I've heard that usually people let the room air for a day with the door / windows open. I painted my entire room in 2 hours, let it air for the night and in the morning moved all my pets back in. I honestly believe if you cover the airholes of the tanks with tight plastic wrap, you give it 24 hours of airing to be safe with everything open, it should be safe.
That's what I would do, but I'm a little paranoid when it comes to animals.
What would also be an option is not covering them, but scrubbing them out completely after the 24 hours. (note, I don't think you even need 24 hours, but that would be the safe bet)

Edit: If you don't want to disasemble them, I would go for full coverage of every possible air hole, even the front sides of the doors. Make sure everything is tight and no airflow can get in. I'm not sure if paint fumes can land and stay on things, but if I was in your position, I'd be overly paranoid, taking extreme precautions is less bad then ending up with a dead pet.