I also downloaded a picture of a bottlenosed dolphin which I then 'traced' over using Serif DrawPlus and the fish drawing. This gave me the 'perfect' outline. BUT!!!!
The following is my first attempt at tatting this. You will see that the beak is totally wrong!!! I thought about using a very long picot for the top fin but if I do this it will need beads added to it and - well, I'm not sure about that. The tail on this first attempt is too floppy and I just didn't bother with the lower fin as I got disheartened!!!
In the next attempt (below) I think I've resolved the floppy tail by using down picots and lock joins. The top fin is now a chain but again I'm not convinced!! I've also used split rings instead of 'ordinary' ones to try and shape the back. The beak is looking better and you can 'just' see where I've used a down picot (which WILL have a bead) for the eye. I think I may well go back to the straight rings and chains on the next version. As I write these patterns down I keep all versions of it so that I can refer back. So, this evening. I need to make one or two of the chains shorter, go back to rings and chains, sort out the fins (top and bottom) and tat, re-tat and re-re-re-tat until I get what I want!!!