Fecundity and Spawning Frequency of the Fathead Minnow—A Fractional Spawner

Six pairs of fathead minnows Pimephales promelas were isolated in 0.3 × 1.5-m spawning (wading) pools partially submerged in an outdoor swimming pool from May 20 through October 20, 1980. Five pairs of fish that survived the experiment produced from 16 to 26 clutches of eggs each between May 22 and August 22. The total number of eggs spawned per female ranged from 6,803 to 10,164 (mean, 8,604). From 9 to 1,136 eggs were spawned per session (clutch). The average number of eggs spawned per session by individual females ranged from 391 to 480. Intervals between spawning sessions ranged from 2 to 16 days (mean, 3.9; mode, 3). Spawning often began before dawn and was usually finished before 1000 hours. The volume of water-hardened eggs was 3.8- to 6.8-fold greater than the volume of the female spawning them. Postspawning mortality did not occur.