FWIW I used to work in a lab where we bred fathead minnows for testing, we had minnows in 10 gallon aquariums in groups of 4. 3 females and 1 male. The only thing in the tanks were two pieces of 4" PVC pipe cut in half to create a kind of cave. The females would lay their eggs under the PVC tiles and the males would fertilize and guard the eggs. We would remove the tiles with eggs daily to keep the adults from eating the newly hatched fry. If ever two males were in the same tank they would destroy the eggs from each other's nests. After removing the tiles with eggs it would take about 2 weeks for them to hatch. We fed the babies newly hatched brine shrimp for a couple weeks and then ground up fish flakes after that. I'm sure this isn't the only way to breed fatheads but I thought I'd offer my experience. Daily spawns of 20-100 eggs were not uncommon.
