https://www.cgtrader.com/3d-print-models/games-toys/toys/the-little-mermaid-poor-unfortunate-souls
Mermaid Soul, dimensions: 28.86 x 101.53 x 56.12mm or 1.14 x 4.00 x 2.21in
Scale up or down as needed.
File size 250k poly.
Render shows two Polyps (Mermaid souls), it's the same file duplicated to show different colors.
File is 1 solid piece, if you need it hollowed out or any other help with the file just let me know.