A 160 should be a good home for up to 6 P bass for a good long while depending on the dimensions of the tank. But they would probably need a bigger tank in the long run as they get very big. I would say you would have a good 2 years if not more with 6 pbass in a 160 if it is at least 24 inches wide. That will give you plenty of time to upgrade when they reach over 20 inches