We have a LARGE pond, and koi questions...

[invadertoast]

Across the street from my house there is a huge man made pond, it's probably 100' x 70' and 3' at its deepest. (approx 90,000 gallons?) It has a stream flowing in, and a culvert/dam keeping the water level where it is. There are no native fish in it, but there are turtles and frogs.

It belongs to my neighbor and she really wants to put koi in it. She had comets many years ago but they got eaten by otters. I'm worried about the otter problem happening again... but ignoring that fact, what are everyone's opinions? Do we need some sort of filtration system? I can talk about tanks all day long but when it comes to ponds I'm pretty lost...

[Northernguy]

Its probably capable of supporting koi the way it is.Filtration is always best but a pond that size would need a lot of it!
The turtles and otters will still be a problem.Birds too!lol

[smaug]

Nothing will live in it fish wise if there are otters.Save the money.

[VoidParadigm]

Koi can get expensive. Unless they're going to buy Koi at full-size (even more expensive) don't bother with it. Just going to become food.

[rothenb1]

Otters love fish... and they'd relish your neighbor's expensive koi!

[smaug]

Otters will also get the full size koi,just easier to catch thats all.

[UncleWillie]

Wait a second. Can you clarify what you mean by a "stream flowing into it" and it being "dammed up"?
From the way you worded it, it sounds like an earthen dam, impounding a natural stream, then overflowing water just goes around a spillway (or equivalent) and back into a stream/swamp/wetland/etc?

Please correct me if I am understanding this wrong...

If I understood right, then your neighbor has some serious legal issues regarding stocking fish into waters of the state that are far more important than any filtration or other hobby issues. Please clarify. Thanks.

[invadertoast]

If I understood right, then your neighbor has some serious legal issues regarding stocking fish into waters of the state that are far more important than any filtration or other hobby issues. Please clarify. Thanks.

Honestly, I have no idea how the whole thing works. I was worried when she said she wanted to put fish in because I thought it was a natural pond, but she told me it was man made and there wouldn't be any issues. I'll have to ask her to explain in more detail, and also explain to her about the otter issue. As much as her and I would love to have a giant koi pond, nobody wants to waste the money on expensive otter food. Thanks for the input everybody!

[UncleWillie]

The only reason I ask is b/c I'd hate for you or your neighbor to get into trouble by breaking the law by stocking fish (exotic or native) into such a setup.

What I was getting at is this: Is the pond made from earth? Or is it a giant ornamental-type pond with a pond liner or something? I know that one persons idea of a pond is different than others (an fisherman vs. a koi or aquatic garden hobbyist's idea of a pond).

If the pond is what I am picturing, it is what I'd call a 'farm pond' (Google image search 'farm pond').
If that is kind of what it is like, then I highly doubt it is fishless. I suggest you/your neighbor search for local regulations on what is "water of the state" and stocking regulations. I say this, because if there is a natural stream flowing in/out of this pond, it is 'water of the state' and it is illegal to stock any fish (non-native or native) into it.

Geez, I sound like a prude..
But I have a strong feeling towards this issue.. this is one of the reasons how we got exotics in our native waterways in the first place..