Generally rule of snakehead is "Kill or be Kill" they will try to eliminate other species or die trying, unless you have a MEGA tank but it's still not guaranty that they will leave other species a lone.
Snakehead will kill it! If you want to comm snakeheads then you need fish as big and aggressive as it to keep them in line. Also get your snakehead as small as possible so they grow up with other large fish. It will reduce the chances of something getting shredded. I have a golden cobra snakehead in my 220g comm and he is fine.. but I have a 12 inch Atabapo red pike cichlid that is staggeringly aggressive and kick everything else's arse.. it's like puffers everyone will tell you 'no don't do it' but they can And frequently will adapt.. but be prepared and bad things can happen.. my basic rule is 'don't comm anything with a puffer that you can't take seeing get chewed to death head first'... but with a snakehead replace chewed with shredded. Your call..
Depends on species,some are a lot more aggressive than others,bullseye and striped snakeheads tend to be more calm while Northern Snakeheads are more aggressive,at least that's what other people say