[MikeM]

Lee: Thinking about the pond I want some day, I start with what I want to keep. Let's say 20 koi 30" in length is the goal. Optimum gallonage is a matter of opinion. Seems to be general concensus that 500 gal per fish is bare minimum to get worthwhile results, with 1,000 gal per fish much better and 1800 gal per fish pushed by some. So, let's go with 20,000 gallons as the goal.



Then I figure a fish should be able to turn around while swimming without having to come to a stop. A width 5 times the fish length seems to allow gliding movement without risk of rubbing against the walls. So, for 30" fish I'm thinking a width of 14-15 feet, with more being better.



Then I figure the fish need to be able to have a burst of real speed when they want. For that, I think at least 10 times body length is appropriate. That calculates to be 25 feet.



Depth is also debateable. It does seem deeper is better where temps get really cold. It does seem to me that depth should be at least twice the body length so the fish have a sense of actual depth from security perspective, and then multiple swimming layers can exist. So, that gives 5-6 feet as minimum depth.



Then to accomodate these figures, one can use any regular shape, but we know that square corners catch glarf, disrupt circulation etc. So, oval or round seems better.



Then adjust to fit available space, enlarge dimensions to get to desired gallonage (hire a mathematician to calculate gallonage :roll: ), and then make it bigger to accomodate the 3 really great ones that put you up to 24 fish :wink: .



Now, if your goal is 40" koi, it may be easier to just board at Momotaro!