Really, I would say with a 180 you shouldn't keep an aro, but that is an opinion. Some people will say you can keep a silver aro in as little as a standard 125, while other people like me say 250 minimum. Anyway, pikes can be very aggressive, but as with arowana different fish have different personalitites. I really wouldn't recommend getting the pike cichlid, unless you can update to a 270 or 300 fairly soon.