Mixing Koi and goldfish - A good idea?

[Andy41]

Hi Guys,

I've recently built a new pond, 21000 litre, and moved my 90 Goldfish into this pond from the old one.

The pond has been up and running for a few months now. Water quality seems good, no fish have died, plants are growing and the water is crystal clear. The pond is 5 feet deep.

I'm now toying with the idea of putting a couple of Koi in the pond, but, i've never kept Koi before, and i'm worried mixing Koi and goldfish - could they attack each other?

Also, how winter hardy are Koi? Can you keep them in a pond that freezes over winter, or do they have to be moved to an indoor tank?

cheers,

Andy.

 

[CountryEscape]

You can keep them together, Andy, they are as hardy if not MORE hardy than goldfish. If I understand it correctly, they are all a form of carp.
The difference with koi is that they get larger, eat more, so poop more and create more waste per fish than the goldfish. Also, they will interbreed with the goldfish, creating "goi", halfbreeds. If you're not concerned about that, no worries adding them to your goldfish. No, they won't fight. I find that the most amazing part of these fish. They do not seem to be territorial in any way, or at least I've never witnessed that aggression in my ponds. I have 2 ponds now, trying to get the rest of the goldfish out of the koi pond, put into the goldfish pond, and then I will know that any babies in the koi pond will be KOI. Other than that, they are all perfectly happy together.
Freezing over in the winter, both fish will do fine, just make sure to make an opening (not by chopping, though) in the ice every so often, preferably once a week, to allow the gases that accumulate with that kind of fish load to escape. And, remember, those 90 goldfish have likely already reproduced and will continue to reproduce, as will the koi when they are large enough. Seems the goldfish reproduce sooner than the koi, or that's my observation anyhow. Good luck!

 

[Fishylove]

Ooo that's a lot o fishys!
I Agree with Country, just be sure that the goldfish are not fancy goldfish,( fancytails, ryunkins etc.) they are smaller, move slower and cannot compeat as well with koi for food or space. Good luck!

 

[sissy]

I have both no issues yet in 8 years.I have fancy tails and butterflies and even shubbies and fantails

 

[CountryEscape]

I also have the fantails with my koi, and no worries. The fantails do move slower, so they might not get the first food dropped, but I guarantee they get right up there to get their share. Plus, I make sure and toss some away to lure the bigger fish away, and then toss some directly to them. They all figure it out in time, as well as the humans who feed them.
BTW, I got a bronze colored fantail a week or so ago, the day after I put him into the pond, saw a solid black fantail! I did NOT buy black, but he was obviously changing to that color. Cool, as the only black fantails I've ever seen have been the buggy eyed ones that I do not like! This one is just a normal fantail, so he will go well with my small collection!

 

[sissy]

I was thinking of a molly also when you said he was black and my spotted ones have never changed color .

 

[CountryEscape]

Nope, I debated about getting it, since it was between a dark orange and bronze color, but I thought what the heck. Either it was going to be solid orange, or stay bronze. I was thrilled when it went to totally black, although it is hard to spot. When I was in the ponds last weekend, it came up and was nibbling on my arms, that's when I got a really close up view. Wanted to make sure no buggy out eyes. LOL

 

[sissy]

my neighbor has a molly for 3 years in her pond ,she had it in a small tank in the house and figured he was lonely .But we don't get that cold so he has been fine .

 

[CountryEscape]

Mollys must be very versatile. I hear they can go in brackish water, too, which is half freshwater, half saltwater. I want to get a few for my brackish tank, but waiting for some nice ones to come in at the pet store.