I have had micropeltes for 7 years now,They will and indeed do kill everything in the tank once the outgrow them.Mine lived with an oscar for years i knew he would eventually tear it in half....Seriously take it or leave it micro will kill and eat what ever is in just as soon as it's big enough...Why have an oscar in there in the first place?? It was given to me at 7 inch i didnt want it but took it anyway and the micro grew up with him,but as already said instinct cant be taken away and he was seen as food at 11inch long,the micro was around 14 inch.Now i do believe it is all different as no 2 snakeheads are the same,i suppose if the tank is big enough and the tank mates are larger there may be no problems but at the end of the day micro is a preadator and if he sees it as food he will eat it....
regards
tim
regards
tim