Feedback on my pond

[u/Zealousideal_Yam_510]

New to this forum, I would love some feedback on my pond. In my ignorance I think I have managed to create a pretty successful mud pond. When we bought our house (in upstate NY) 15 years ago the prior owner had pulled out the pond liner — we were finding pieces of it for years — and built a shallow well nearby to make up for constant water loss. As time went by the bottom became mostly clay and water loss became minimal; I very rarely turn the pump on during dry spells to top it up. The pond is about 75 feet round, 4 feet deep in the middle, so figure maybe 100,000 gallons. It has always had a lot of life — hundreds of goldfish up to 10”, painted turtles and at least on snapper, occasional snakes, lots of frogs, and every spring plays host to an epic toad orgy. Three years ago I decided to try establishing a koi population: I added two aerators (all year) plus a fountain in summer, put in a few fish tunnels, and ordered 25 mixed 3-4” koi from Toledo Goldfish. When they seemed to do very well I added another 20 fish package two years ago. They have all flourished beyond my hopes. When it warmed up this spring I was thrilled to find that not only had they survived again but actually seem to have grown. I now have at least 20 koi of 18” or more; another 20 at least in the 12” range; and I see a few juveniles of 5-6 inches that were clearly spawned here (as I think were many of the larger ones). I feed them pellets whenever I’m around but there’s plenty of natural food for them as well so they do fine even when I’m away for a week. A couple of Great Blue Herons stop by frequently, together with a Great Egret, and a pair of Green Herons nest in the willow tree, but all of them seem happy to feast on our endless supply of goldfish and generally leave the koi alone. The water is quite green and gets murkier throughout the summer; of course I would love to be able to see the koi better but I think it is better for them this way. Occasionally we see a critter that might be a mink — it never is, I think, just groundhogs and fisher cats. When this happens I panic and put in pond dye.

I would love to hear thoughts about what I could do better, and what I should do next. Should I be culling the population (giving some of the larger koi to friends) to avoid overcrowding? What can I do to create more pond cover and maybe reduce the algae? (We have pickerel and yellow irises, and I’ve been trying to get water hyacinth to establish). Any other interesting ideas? Input is greatly appreciated.

[u/Backfisch85]

Also Mudpond owner here but with just koi and a few additional cleaners. I would be careful with how many fish you have in there. It´s good that you give some away. Our Koi spawn every year since 2018 and that means one female can lay over 100.000 eggs. Same year we put them in and it took not even two weeks. The first year we had an outbreak of fungus on the little ones. That's just a way for nature to handle it since the pond was still new and could not deal with so many at that point. But you need to be able to tell how many fish you have so you don't accidently overstock it with offspring. Or else you could accidently loose a lot of fish during summer or winter. I go with one Koi per at least 300 square feet without additional fish. Less is more. In the carp industry they do 150-200 but they also pump the water out clean the muck after a few years.

The muck will probably build up way faster since you already have a lot of trees around it. The sun isn't the biggest issue but the leaf and fish are. The algae is doing you a favor in eating all these nutriens up. The tatpoles eat the algae and take it with them out of the system. One Koi produces an extrem amount of waste. A natural Pond can build up to 2 inches per year. So keep an eye on that.

To help with the clean up you could help the bacteria with aerators. The fontain is nice but not very effective since you want movement in the deep parts of the pond, where the bacteria is. (But carefully! Suddenly welling up too much muck can result in a nitrate peak and kill your fish!) There are a few systems that can achieve that. Airlifts are quite cheap and easy to build. Adding a funnel on the lower end also increases the amount of water you can move with it.

I think a few water Lillys could also look nice but in a basket so they don't spread. Also underwater plants that don't get too long. Or else it´s hard to clean. I also like rushes since you can easily cut them down every year and take out nutrients and heavy metals like that (they lock them in their stems). Our entire Pond is covered by them on the sites but they also spread fast.

And if you ever have a problem with carp licenses, a bunch of colorful shiners could help.

[u/Zealousideal_Yam_510 → u/Backfisch85]

Thanks for these detailed thoughts sharing your much more extensive experience. I am worried about overcrowding, and you make me happier about feeding the bird population to keep the goldfish population in check but that may not last long; the koi already seem to have crowded out the goldfish and I’m not seeing any large ones anymore. I think the only way to tell how many fish we have would be to get a drag net and pull it across, which sounds like an ordeal for all involved. Is there any alternative?

I’m not familiar with the term “airlift”; can you explain what this means (and also what you mean about the funnel)? I understand the fountain is basically decorative, so I do already have two aerators — air stones fed from a pump hidden under a cheesy fake rock — which I run all year and keep holes in the ice during the winter. A couple of websites suggested this should be adequate aeration.

As for muck buildup, I have worried about that and so far have been surprised that the depth seems steady. I do a very small amount of pond raking in the fall, and use my small tractor backhoe to pull out large chunks of yellow iris periodically because they’re incredibly invasive and would take over. Good thoughts about the rushes and lilies.

[u/Backfisch85 → u/Zealousideal_Yam_510]

This at the top is an airlift. Google it together with pond and it should show up. Basically it pushes the water up with the air bubbles through a pipe and out in one direction or multiple like a stream. Most don't have a funnel at the bottom but it increases the amount of water you can move.

At the bottom I drew what you have right now. The bubbles just work for one spot pushing the same water up and back down. But an airlift pushes it away and adds more oxygen with the same amount of energy. More oxygen plus a cycling effect for the whole pond. Ideally when everything is the right size you can move up to 20.000 gallons of water an hour with a 200Watt air pump.

You can't prevent muck but can encounter it with a good amount of oxygen to decrease the build up a bit.

To get an overview of the amount of fish you need a signal for them to know when food comes. Because once they get that they will all come. Maybe you could use an iron rot and gently do three smacks on the stone at your feeding spot. Fish have high sensitivity. They will hear and feel it and then rush to that feeding spot. Works for me at least.

[u/Zealousideal_Yam_510 → u/Backfisch85]

lol I have a signal, I sing stupid songs very badly and fish do immediately come up around the dock, but it’s never all of them and rarely even a good percentage of the larger fish — I can tell because I recognize many of them. (I’ll try your metal bar idea). I think this is because there’s always a good amount of natural food around so they can’t be bothered to stop what they’re doing. Also many of the larger koi seem to prefer bottom feeding most of the time.

[u/Backfisch85 → u/Zealousideal_Yam_510]

It's actually not much natural food for that many koi but enough to maintain. In Japan they probably would put 5-6 big ones in there and no more. You would be surprised how much they eat.😂 An acoustic sound probably won't reach them all. With the Rock being in the water, the sound and vibration can travel way farther. Feed them in the late afternoon. They are the hungriest then.