id say depends on size. if there both a foot id say the piranha there more developed and the snakehead is still a babey if we go 24 inches and up deffitly the snakehad maby wouldnt even have to go that far. when there both large snakehead no compitition, no piranha could stand up to that not a rhom nothin. even though there both packin some serious jaws the snakeheads still goni to be way more bold and get bsuness done as were rhom may hmm and humm about it till it deosn anyhting or feels it needs to, and by then it will be in 2 peices. sure rhoms are bolder then a red belly but thats not saying mutch. not to say i dont like piranhas and all.