The minnows would likely be eaten by resident fish immediately after stocking, and thus would serve only as short-lived, expensive fish food. The availability of appropriate spawning habitat. The timing of the stocking. The ratio of males to females. Fathead minnow females will fashion nests on the underside of rocks, twigs, boards or tile and deposit their eggs on submerged objects.
Males remain with the eggs until they hatch.
If you wish, you can improve spawning success by providing the minnows with good nesting habitat, such as cedar shingles. In Missouri, spawning usually occurs from the second week in May to early August. To achieve a suitable ratio of males to females, make sure that the minnows stocked vary in size. Fathead males are larger than females, so stocking mostly large minnows could result in poor spawning success. Mortality of fathead minnows is high and the maximum life span for the species seems to be three summers.