some oscars will actually stay that way... I have 2 alone in a 125 gal. One 6" albino swims up to me everytime I approach the tank begging for food. The other 10" tiger sinks to the bottom and plays dead. I've had him for 7 months and he has only eaten in front of me once or twice. He will only eat at night with the lights off and nobody in the room. Same species huge difference in personalities. Thats why we like oscars though.