I really love this pattern! It's the widest one I've made and my goal was 6 fishes, so I made each string 60 inches, with the three middle blue strings (B, F, E) a couple inches longer. I also did straight edge, so the 2 strings I added to the sides were only 30 inches (which was still longer than I needed, but just to be safe). That was about right for the three middle blues and the middle black (A) but the colors C and D could've been a lot shorter, along with the outside black and the outside light blue B.
So to sum up: make the E A F B B F A E section of strings longest, the others shorter