Without properly setting up breeding tanks, I have some success by placing a layer of glass marbles over the substrate, the eggs that fall through escape adults eating them.
Also from keeping the gravel siphon I get fry hatch out over about 1 week. I have 20 "Sunset" Mountain Minnows about 10 weeks old now, and 3 in my main aquarium with the 5 adults & more appearing each day, & about 6 clinging to the 'siphoned' bowl.