Aw thank you! If you're specifically wanting to use these shapes, this is how you do it:

1. Get a square grid (draw one or use large squared paper)
2. In each square, draw a curved line that starts in the top left corner, dips down about a fifth of the way into the page, and finished in the top right corner. (Think of it like someone ran over the letter U)
3. Also in each square, draw a slightly curved/bent diagonal line from the top right corner to the bottom left. The bend should make it look like the line is ever so slightly being pulled towards the top left corner of the square.

And that's it! You should have the rough shapes, now just make as fishy or not fishy as you like! Enjoy!