I thought they might (this tank is 24" high) so I was prepared to move them to a 10G - but they have no trouble. They float on top, climb the plants and sit in them and jump up the sides of the tank when they need to. They seem much happier in here than in the 4G they were in prior.
They are all doing fine and are very friendly. It did take a long time for them to acclimate.. I ended up leaving the lights off and the tank very quite for about 18 hours before they started to settle down and come out into the open. Now they are generally alwasy out in the center of the tank the Notho pair is almost alwasy together whereas the others tend to be more solitary.