My LFS gets in wild-caught sailfin mollies and swordtails from Mexico. Would they be OK in the same tank? I'm thinking of starting up a 33-long mixed livebearer tank with a trio of each, or, two pairs of sailfins and a trio of swordtails. (The LFS only sells the mollies as pairs, so I'm not sure if I could get a trio.)
I also have four tequila goodeids I was considering adding to that tank if I do move forward.
I've read that it's difficult if nearly impossible for mollies and swordtails to hybridize, so I'm not too worried about that. (Unless you think I should be!) I'm more concerned about the males competing with each other, or, harassing the other females too much.
I do have extra tanks for raising fry, so I don't expect the display tank to be a colony situation.