You should keep a goldfish instead. Clearly you don't know what a cichlid is or needs, and you also don't seem to care.
First of all your tank is too small for ANY oscar, they will all eventually die because they will be cramped and find it impossible to move around comfortably. Not to mention their huge bioloads, you won't be able to keep up with the maintenance. And then there's the feeder goldfish. Basically you're doing everything wrong. My advice is to do a lot of research on whatever you plan on keeping BEFORE you get it, stick to smaller cichlids... set up a water change schedule and get a high quality pellet food. Good luck.