Pikes have highly belligerent attitudes towards conspecifics and other species that resemble them in appearance. You are dealing with Crenicichla cincta, not just some wimpy Crenicichla lucius or similar. Crenicichla cincta is renowned for its aggression, and if you don't want to lose your snakehead, DON'T put that pike into the tank. Even if your snakehead is larger than the pike, expect fighting to break out. The real bad news is, your snakehead wil lose out at the end of the day. Your species of snakehead is not really an aggressive one, and even if it is, it will still succumb to the teeth, speed and power of the Crenicichla cincta. I strongly advise you to think again.