yeah you will need to separate them, sens look all mellow and innocent but have no qualms about eating a fish if it is small enough, in my 120g i have some large aggressive cichlids (not full grown yet but ranging from 3-6.5in) and whenever i try to add any kind of new dither or other small cichlids, i never have problems from even the largest cichlid trying to eat them but the sens go after them, sometimes right away, sometimes they wait till night time but the case is even with a 6.5in carpintis in my tank my sens are the only ones i have to watch out for when adding new smaller fish