I just caught Speedy Lou, one of the Legendary fish.
Here are some shots. But first, to get the fish, first you'll need to click extremely fast, and there will be a rod GUI, so the faster you click, the closer you get to green, and once you get to green, you need to move the mouse in a circle motion to "reel it in".
It took a while, and I was afraid he was gonna get away, but I got him!
You also get to wave good bye to the fish, and see him swim out. It was too much of a happy ending. I wanted to fry him up and eat him.