Please have a look here:
But currently, there is a time out issue, and it disables it for most of us here (including me) to get the file.
I’m really sorry that you have to experience this.
The lesson can be mostly done with a flat (cube) object set up with many segments and made editable.
Please let me know if that current workaround needs some guidance from my side, I will have a look in any follow-up question of course.
At the moment I get this file downloaded, I will update all threads with this question. Again: Sorry.
If you like, I can model a fish for you, it would be no problem and a pleasure to do. Just let me know.
Enjoy your weekend