Might be, or the number and size of fish is small. The eggs are hard to
see. They are clear and sticky. If you lift out the plant pots, any rocks,
or any other object and look at it closely, you will see eggs everywhere.

I do keep a low number of fish....10 full sized ( herons got 9 last year) and 3
babies from last year. The pond is 10,000 gallons. 2 females are in the 30
inch range, the rest are small (18 to 20 inches) and mostly male I think. I
keep my koi stock low, so I can run a "natural" unfiltered ( veggie only) pond.
......Besides, when I come to the pond they all follow me around it, so it looks
crowded ) I have the water up about 2 inche higher than usual, because
the females get into the pots, and all the others follow her in. I want to
have a little cushion for her to get in easier. The females are really
swelling with eggs. I never noticed if the moon was full when they spawned,
but they do tear up the anacharis and it floats several days befor the spawn.
I never noticed the month either....I am in zone 7B Atlanta area. I don't test
the water, etc etc etc.....Just me and my pretty fish Jerri

http://www.fringeweb.com/Ponds/JerrisPond