I would say it depends on how they are prepared and the set up. I spawn mine in an extra deep plastic sweater box. I put the male in for a few days and once he appears adjusted I place the female in the box inside of a mason jar. The male will wear himself down within two days and build a nest while he is doing so. To keep stress down for both fish, fill the jar with the female in it about 1 1/2"-2" higher than the water line in the sweater box. She will go to the top and they can no longer see each other. When I place them together, I use two mason jars with water angled so the female can swim around to avaid the male if necessary.