I've keep koi, have done for about 7 years now. Pond is 1800 gallons so a mere puddle compared to 7000 gallons! I'd love a viewing window.
Fish range from about 12" to about 24", all cheapies I couldn't bring myself to pay hundreds for a fish to find it belly up or heron bait! Don't take a lot of looking after to be honest. Some people seem to have all sorts of problems which I don't seem to have had....yet.
Other interests golf, xbox, drinking.