Quick update, I kept the tank as it was and didn't add any extra Barb's thinking if it isn't broke dont fix it , and the tank has been very happy until today, when the Pike decided it wanted the tank to itself and has killed one barb and I have one swimming upside down barely moving , I'm quite confident it will also die ( put him on his own ) I've removed the last healthy Barb and put him in my 6x2x2 . ? not a good start. I won't be adding or trying any other fish with her from now on.