The ammonia levels in that tank are going to be out of control. Koi really aren't good for indoor situations unless you have several hundred gallons. Make sure you all are extra careful not to put your hands near the water if you have open cuts as poorly farmed koi often have a number of diseases. Never let them go in the wild if they get too big.

I love looking at the koi from Nihon Koi Farm in Japan. I'd like to get one from them one day if I ever had several thousand to spend on a fish.