I have seen mollies kept long term with mbuna, no problems. I think it is hit or miss. Swordtails should be the same, even if they are faster than the fancier mollies. Personally a big non fancy molly type, like salt and pepper or black lyretail would work best. Don't underestimate those big livebearers. I have seen videos of mollies beating mbuna in fights. Rare, but it can happen.
I also saw thread on a reef forum where someone put some creamscicle sailfins in a reef (most Poescillidae can take full salt) so t the babies should be extra food, and they terrorized his clowns, damsels, and gobies so bad that they hid until he took the mollies out. My lfs offered me a killer black lyretail that had knocked out half a school of tiger barbs, and i declined the offer I didn't want to lose my rainbows
I also saw thread on a reef forum where someone put some creamscicle sailfins in a reef (most Poescillidae can take full salt) so t the babies should be extra food, and they terrorized his clowns, damsels, and gobies so bad that they hid until he took the mollies out. My lfs offered me a killer black lyretail that had knocked out half a school of tiger barbs, and i declined the offer I didn't want to lose my rainbows
