I would say FH as they spawn at a cooler temp than BG or RES. Just now time for BG in the south. But I know Bob reported last year that he saw some new spawn BG in late Jan./Feb. Here is the info.
Pimephales promelas
Fathead minnow
High, minimum population doubling time less than 15 months
Reproductive Habits:
· Mature in 1 year
· Spawning occurs May through August in water 15-32°C
· Fecundity is 6,803-10,164 eggs per female
Fathead minnow
(Pimephales promelas)
Common name: Fathead minnow
Scientific name: Pimephales promelas
Production potential: Easy
Marketing potential: Potential: High
Size: 1-3 inches
Market: Bait
Temperature Requirements: Growing: 70oF
Spawning: 65oF
Lethal: NA
Feed requirements: Protein: 30-38%
Fat: 3-8%
Spawning requirements: Spawns during cool periods in summer and sometimes fall, eggs hatch in 5-6 days. Females lay from 200-500 eggs per spawn, spawn repeatedly during spawning season.Two methods are used to produce fry. The first is the wild or free-spawning method which 500-2,000 broodstock are stocked into ponds. Egg hatching and growing of yound to marketable size occur in the same pond. The second methodbis the fry transfer method. In this method, 20,000-25,000 broodstock are stocked into ponds in a ratio of five females per male. Fry produced in either method are trapped and counted then transferred to rearing ponds. In either method, rocks, tile, bricks, or boards are placed into ponds to provide spawning sites.
Most common
production systems:
Ponds. Fry are stocked at a rate of 50,000-300,000 per acre.
http://ag.ansc.purdue.edu/aquanic/publicat/state/il-in/as-507.htm