Ha, I recently picked up a baby diamondback water snake at a reptile show to eat excess endler's livebearers. I have 3 tanks, 75 and 2 40's, crowded with them. Even scooping out netfuls and dropping into other tanks for larger fish to eat doesn't slow them down enough, but feeding the largest females should slow down their population growth a bit.
Molly fry were worse IME, my other/larger fish wouldn't even eat those.