Does this look like a fishtail lace sock to you?
No, it doesn't look like one to me, either. It looks a lot more like the baby version of Lara, by Debbie Bliss, from her book Special Knits... and oh yes, being knit at DK gauge instead of Aran. I really have to face that problem of mine head-on, some day.
The yarn is Rowan Cashsoft Baby (DK weight) in a lovely sage green, being knit on size 6 needles. I am following the directions for the largest size, which is coming out to the measurements of the 6-9 mos. size. Lovely. And fast! And it looks like I might have a ball of yarn left over, even. Three cheers!
By the way, Koigu is on sale for $8.80 here: