An adult p-bass can be pretty big!! Just make sure that it has room to turn and swim! Babies can make it for a while in smaller tanks til they start rapidly growing! Check the max size and you make the final decision on whats best!
Like I once said to Neal...cichla do probably need atleast 600 gallons or more.
But lets be realistic...not everyone can provide a tank of this size. Whether we like it or not, these fish will be available to everyone.
So when people ask me what the minimum tank size should be I always suggest a 240g. This is something realistic that is quite possible for most hobbyists thinking of keeping cichla.
Suggesting 600+ tanks is unrealistic and im pretty sure most people would ignore that anyway.