'How I built a 4,000 gallon Koi Pond,' DIY fishpond project (photos)

Originally published at: https://boingboing.net/2019/06/28/how-i-built-a-4000-gallon-k.html


I had a koi pond in Texas. One day I came home to find a dead fish floating in the middle of the pond. I walked over to check it out and spooked the vultures waiting in the trees which spooked me. I got it out of the pond and put it in the yard. Within a few minutes the vultures were on it for a nice dinner.


I live in central Texas.
I have looked at this pond and thought two things instantly:

  1. Not deep enough or with enough underwater cover to evade raccoons, which will kill every last one of those fish.
  2. Not deep enough for the herons either.


It is a known issue.
Maybe this koi pond is located in a safer area.

I am of course grateful we still have some real [native] wildlife, but man those raccoons are pretty hard to take. It’s summer here now, and they are hungry, thirsty, and getting into everything. They are extremely strong, sharp teeth and claws, opposable thumbs, and clever.


My first thoughts when I think of carp


Gross. So glad I’m half Sephardic and that fish hotdog is only at half my family holidays


Long ago, I bought a house with a cement pond. Cleaned it up and filled it with goldfish from the bait shop. Over several years, the goldfish disappeared (I blame herons). But their gray-brown progeny survived by being less visible. There’s safety in blandness.




192 gallons of water a day go into the pond according to the post. That’s not great.


How do you protect your fishpond from raccoons? Tiny Hunter killer subs? Miniature gunboats?


He said that it replaces 150% of the pond’s volume every month.

3900 gallons * 150% = 5850 gallons per month.

That’s a lot of water.

If they didn’t have space issues, they could have set up a cattail pond or something to run the water through.

It does look really nice, though. I am quite jealous.


Motion sensor sprinklers seem like they would work.

A dog would probably work better, assuming they have a dog door and can go out at will. Unless the raccoons befriend the dog and he invites them in…


MUCH bigger than my dads. He just has a round tub in the ground, essentially, filled with gold fish that grow pretty darn big. I forgot how many gallons… couple hundred maybe? IIIRC he has a filter, but doesn’t cycle out the water, just fills needed. Or not, with all the rain lately.

Watch out for fish stealing herons!

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  1. Make sure the pond enough depth that a raccoon can’t take a swipe out of the water and grab a fish. One pond expert I spoke with says 4 feet deep (~1.2 meters) is usually sufficient. Raccoons work the edge of water but they are not aquatic animals, and mostly avoid swimming.

  2. Make sure fish have “cover” in the form of deeply submerged sideways large dimension pots (clay, plastic… held down with stones or wire,), large submerged hollow logs, or large dimension (wide) propped stone ledges in the deepest part of the pond, for fish to hide under.

  3. For shallower ponds, netting or welded metal wire “lids” or covers are useful. Most raccoons are nocturnal although I had two young raccoons stripping my pear tree at 10am on a Saturday, so apparently not all raccoons get the memo.

  4. I am told these work pretty well but you have to move them slightly to new positions every day to keep the narrative convincing:

  1. Keep all fish food and other foods attractive to raccoons (pet food, seeds spilled from bird feeders, sugarwater hummingbird feeders, garbage, compost) well away from the pond, and in a secured (bungee-corded) container.

I wish I knew less first-hand about raccoons.

Koi are expensive. Really, most people can get away with goldfish-like pond fish and most people don’t know the wiser. Time will tell whether this DIY project is sustainable long-term. When in doubt, use the starter fish first. At least the attrition rate will be less costly, financially.


Where there’s a will, there’s a way (at least when it comes to koi getting predated).

If I recall correctly, they ended up emptying out the whole pond and waiting for a few months to get rid of this critter.


That’s one extreme story!

Thank you for this. It’s… so… typically otter-y!

Spam of the Sea!


With apologies to John Pinette:

“You! Furry boy! You been here for four hour! You eat all the fish! You go now!”


Koi loaf!



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