As soon as I saw this design, Koi Pool by Nim Teasdale, I fell in love.  :-)  I am truly enamored of the way she used pooling to create an absolutely gorgeous piece. 

I'll quote her here:

Koi Pool is a strikingly simple and elegant wrap, designed to use two contrasting colours to spectacular effect.

Koi Pool is worked in squishy garter stripes with an eye catching band of mosaic fish scales running along its length, formed simply by slipping stitches, in a textured combination of garter and stockinette. The wrap has been designed to be adaptable as to width and length.

The pictured sample used a solid colour in contrast with a variegated skein used in a pooling formation. The design is also ideal for showing off two contrasting solid or semi solid skeins, or a solid paired with a speckled or gradient yarn.

She also mentions that the pattern is written for fingering weight yarn of approx 1000m. Bear in mind that both the width and length are adaptable, so that yardage is only to match the sample size. 

The design can be worked entirely from the written pattern, or from charts with some notes.

Anywhere between 656 - 1312 yards (600 - 1200 m) of yardage is suggested. Nim says that the designs works best with one solid colored yarn and one where a variegated skein was dyed in a long closed loop.