GW FH are fractional spawners and can spawn for mths if photoperiod and temps are ok. You probably have them of all ages from last year to now. BG have multiple spawns in your location so same result they could be all different sizes . Those fish look to big for 2-3 week old FH as best I can tell from the pic . At 2 weeks post hatch they would look like specks in the water. In addition fish spawn more and grow quicker into an empty envior. ( new or empty pond) as that is a survival of the species trait. That is why it is so important to stock correctly so that your first fish can spawn and grow to create a base to work from.


Sea Grant Tip Sheet Series
AS-507

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 young to marketable size occur in the same pond. The second methodb is 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.