In raising Killifish you can do one of two things with the plant spawners. Pick eggs from mops and hatch them in containers or let them hatch and grow with the adults. I use a combination of the two. I put a mop in with the adults and let them spawn into it for a week. At the end of the week I move the mop to a 2 1/2 gallon tank. Fry appear in about another week. I don't pick the eggs because the fish I raise, Aplocheilus lineatus Golden Wonder, have a tiny thread that attaches the egg to the yarn mop. I have no evidence but I suspect that picking the egg damages them when you tear that thread. I never get fungus and I get a good hatch rate. The small hatching tank concentrates the small live foods I feed my fry and growth is rapid. I currently have over two dozen fry growing out to put in my new tanks. Six tanks with only one species. Weird huh ? One fish is from a pet shop purchase in December 2019. All of its companions have since perished and the remainder were all born in my fish room. It isn't boring having only one species of fish. I see behaviors and antics among them that maybe wouldn't happen with other fish around.