I will respond only from my own experience. I assume that the original goldfish eat the fry, but I don't actually know that this is the cause for some population control. I initially had three comets in my 700 gal pond. At some point, there were approximately 20 new fish. I had a second bigger water storage pond that I used for watering etc. and I moved three or four of the new comets to that pond (it gets little care or attention). A year or two later the storage pond had perhaps 40 little fish. The regular pond must occasionally end up with a new fish, because last year I noticed a fish that wasn't changing color and he is only beginning to change this year. I am sure he wasn't there two years ago unless little fish can turn red and then turn back to brown. We have a hawk that I suspect rarely grabs a fish. In any case, I currently have 14 fish rather than the 17 I initially observed.

My assumption is that very few fish can't control population well, but a larger number will be very effective. The 40 fish didn't increase the next year. Actually, the year after that, I forgot to turn off my watering and nearly drained the storage pond and probably killed approximately half of those fish. The remaining fish population has remained essentially constant.

My conclusion is that a minimal number of fish may not contain an initial population to a 'perfect' count, but that a larger number will Then maintain that larger population.

That's my experience too. Goldfish certainly eat the eggs and fry. The parents themselves will eat eggs as soon as they're laid.

More fish in a space will be better at finding every egg, fry. More cover the more eggs/fry will survive.

Fry also have pretty specific food requirements. If that food is scarce the fry often die, we'd never see their bodies.

Nature will also limit the adult population if water quality isn't good enough for a fish load.

Hi
Here's my experience . I kept tropical fish until the deep freeze of 09.. Added 7 for a buck "feeder " GF . In March of 12 had to do some repairs so got an exact count. 104
This spring have noted considerable growth on several individuals and a lot of spawning activity. Only one is definitely from the original stock as he is entirely white with short fins . he is around 12 inches now . Interestingly
only one with the original coloring. While there are many partly white none are entirely so he's easy to keep track of . Black and black spotted completely disappeared most are various shades of gold. so I can immediately tell when a fish is young . Very difficult to count but still seem to be less than 100 Do seeem to be holding steady?? gary

I started with 3 "standard" goldfish in a 150 gallon pond. After a couple of years, moved them into a 4,000 gallon pond (above-ground swimming pool we never used). I could see them racing around the edge, leaping out of the water in what I fondly believe was joy.

The next year, they spawned, and we had about 15 youngsters. The following year, they spawned and spawned and spawned--at least 3 times, probably more, until I estimated we had well over 100 fish. I had nightmares of 4000 gallons of writhing orange bodies.

The last couple of years, I haven't seen any fry, so either they aren't spawning or the eggs and fry are all getting et.

BTW, I read that only one kind of goldfish will keep the black coloring. I can't remember which kind, though. My fish have all turned red-orange, gold, and white.

Black Moor is the only one that comes to mind.

It sounds like it'll take care of itself, then. Thanks guys :)

In my 750 gallon 5b pond, the numbers gradually increase over the summer, with dozens of small fry before the pond freezes. After the thaw, the numbers are down to normal (15-20) again.

There's a nice balance of fish and plants. I never feed the fish and the plants do nicely without fertilizer, which makes filtering and cleaning much easier. Every summer a few big fish die (old age?) and some mid-size ones grow to take their place.

Big to me are the 4-5 year old, 3 inch long ones, some of the originals from the dozen feeder goldfish bought at PetSmart. 2 died last summer, 2 the summer before that. No signs of disease. The others thrive.