Hello Subhankar Samantara,
Parrot and Oscar are both aggressive with territory lover fish. It has been see if parrot and oscar are not kept since small in community tank than they won’t stay in community tank.
It is difficult to answer you question now as I am dont know the size of both fish, what is tank size and how many fish you have already tank and how many you going to add?
But still advice you not to do experiment with such mix and match combinations.
Please provide details so I can provide better solution on this.
Thanks for asking question.
Yashwant Naik