Better compromise ?
That was using a qualifier key on the orange fins. Actually it proved impossible to get uniform isolation that worked throughout the clip - it would definitely require tracking the fish with a rotoscoped power window and modifying the qualifier at (many) soft key points. A lot of work.
Don't want to back at it, but I don't think I would have been able to turn the fins more yellow using just the channel mixer and primary wheels without fighting a green bias over the rest of the image, which is what I was laboring to avoid.
Shekh seemed to get there though.