Just wondering, but how much space do koi actually need? B'cuz iv heard loads of differant measurements. And do they need that much space all the time? Or could you keep them somewere smaller while they were very small?

I know a guy who kept two in a 30-40 gal aquarium until they were around 5 inches.They were bought in for the winter and were also quarintined during that time. After winter they released into the big pond and are stocked right now at about 400 gallons per fish. I have 4 3-4 inch koi in my 800-900 gallon pond so at that size I am not worrying but in about a year that will all change. I will probably have to dig out more and use all of the extra liner I have, if my filtration can not keep up.Koi can put on 6-8 inches easily in a year so do not plan on keeping them in small conditions for a long time. If you do be sure to do plenty of water changes and have a big filtration system. So with my expierence and others I say 200g per fish at the extreme least.....if you have good filtration.

koi need 1000 gallons each and a massive filtration system

i would like to say adult koi need 1000gals minimum were as the baby ones need at least 200gals minimum more being better as the first growth spurt is the most important.

One thousand US gallons PER fish and intensive filtration (read: expensive to buy and operate) to keep them healthy. You can start them in smaller quarters, but be digging a bigger, deeper pond during the year or two they're in smaller tanks. They'll need that room within two years.

I've been to shows and have seen how big these fish really get and it's impressive -- and a little scary if your pond is too small. I have a 2000 gallon pond and refuse to stock koi. I'm sticking with goldfish. I get all the fun without any of the hassle.

Oh, ok I think my friend must have overstocked his pond then, because he ahs had his koi for about 2 years and they are about 2 and a half inches long, with a little belly on them, but he does have a lot of fish in it. I always thought he had over stocked, but he never believes me about the space fish need. He kept to common goldfish in a 4.5 litre bowl for 4 months, using tap water without any de-toxifying agents!Oh, and soon he is getting two 6inch tench and 4 12inch golden orfe!