Most pond fish require both the right photo period and temp to spawn. For example "

" Sunfish spawn several times after water temperatures
reach 21°C (Dupree and Huner 1984).

The suitable temperature range for reproduction

by bluegill L macrochirus is 20-30°C (Breder and

Rosen 1966; Banner and Hyatt 1975). Reproduction

also requires a period of 12-16 h light (West

and Hester 1966: Banner and Hyatt 1975). ...



Female bluegills

began spawning within 3 months of the initiation

of the water temperature and photoperiod

regimes, and several females spawned more than

once (up to five times per female) over a 5-month

period. "

" In a descriptive study of a closely

related species, Lepomis macrochir•s, James

(1946) described a period of gonadal quiescence

during the winter followed by a period

of active gametogenesis in the spring, concomitant

with the seasonal increases in daylength

and temperature."

This occured about every 28 days after the required temp and photoperiod were reached.


How moon phase fits in biologically I don't know. I do know I have observed many times the peak spawning activity occurring on the full moon in the mths when the photo period and water temps are optimally reached. I addition I have read accounts in studies by fisheries biologists confirming those observations.