Nice looking goldfish! I was just looking at New York's
baitfish regulations. They're a bit confusing, and I would call the game and fish and ask to talk to a fisheries biologist before I did anything, but the "green list" in the regs contains many species that would be interesting, beautiful, and probably thrive in your pond...and they'd be a whole lot better at avoiding predators than those goldfish, too.
It is NEVER a good idea to involve the State of New York in any part of one's property management. My little bog and overflow might well be tagged as a wetland by DEC even though it is artificial. The pond itself would involve a permitting process and the envisioned creek would likely be regulated being as close to the Snook Kill as it is. The State of New York would enrich themselves with literally 1000's of my dollars for what amounts to a puddle that has carefully been designed to avoid any leakage from my property and actually improves the wildlife habitat while doing no damage to nature. NYS is a meddlesome nanny that thinks it always knows best. I could tell you some hair raising stories from the days we had a camp on Trident Pond in the Tupper Lake Region in the heart of the Adirondack Park. Thanks, but no Thanks.
The pond has a liner which I think is a limiting factor for many native fish although Fat Head Minnows might be a good option and are under consideration. Linda did receive some red nose minnows, 1 dozen, in trade for a group of Fat Belly Molly at a locally owned pet store chain. She has an arrangement there for her broods of Molly, Guppy and Swordtails.
The Goldfish were actually an impulse after pond completion last year. They were from the feeder stock at the afore mentioned pet store. We purchased 5 goldfish and a dozen, (I think), Rosey minnows at 20 cents each and literally dumped them in the new pond with little expectation. Shoortly thereafter the pond turned to pea soup, (I knew nothing about water care at the time, still know little I should add). That is when I connected the artesian well and installed the bio filter and UV system. After several algaecide treatments together with the filters the pond cleared and lo and behold we had 5 smallish goldfish and several minnows. In the fall we were visited by southern flying geese and they devoured all but two minnows but no golds. I think there was sufficient cover for the fish to hide at that point. All 7 fish survived the winter, and the Goldfish are now about 8 inches long and breeding, (happily in Linda's view, not so much in mine).
I will investigate some other fish but I really want to limit the population of the pond for maintenance reasons. The artificial bottom is a limiting factor and many species, such as Sunfish, I have investigated require a "dirt" bottom that would require me to make dams to hold the substrate in place and due to the depth at the shelves subject them to predation.
I do not pretend to be an expert, (Expert -- X is an unknown quantity and spurt is a drip under pressure
), so my thinking may be incorrect.
In any event I am on the lookout for any ideas for other fish that will be happy in a roughly 1800-gallon pond with thin covering of blanket weed on top of a liner that has an approximate 100percent water change every 7 - 10 days and tops out at about 78 - 80F degrees, gets about 10 hours of full sun daily in the heat of summer and can survive a normal North Country winter.
I do thank You for the input and am open to suggestions that do not involve our meddling State.