First WIP for the feesh! Bits are missing and there's a lot of polishing still to be done, but I'm happy with the overall progress so far.
I couldn't help myself and modeled the "fin-array" running along the back procedurally using GeoNodes. The second video/GIF shows how the fins stick to the torso even as I remodel it.
The underwater environment is effectively finished, I added another render for it in the attachments. Among other things, I've added some rocks, refined the instancing model to minimize clipping and ensured all the flowers "face" the center.