The classic version allows you to choose one of the five koi - this will let you know where the slot's title comes from! Each of the five koi looks the same, but with a different colored background. Your first choice is to have 25 free games, each of which will see any victory using the Koi wild symbol multiplied by 2x, 3x or 5x.
The other four options show that the number of free spins available is reduced, although the multiplier is increased. The minimum available number of rotations is 10, and the multipliers are 10x, 15x and 30x. As always, these "choose your volatility" options, the long-term victory should be the same. The luxury version actually has seven koi instead of five.