This issue has plagued me for years. I hate it when you have a great school of fish, and the ones in the foreground have a red shift, and the others are naturally colored.
I am too cheap to get the Keldan filters right now, so...
I have been experimenting successfully with using different shades of Cinematography lighting gels by LEE, and rubberbanding them to my video lights to compensate for the red shift.
Here is a link to the Keldan site with their solution to our problem:
https://keldanlights.com/products/filters/filters-for-video-lights/1496-ambient-filter-af-12-b-72mm-4x-8x.html
The other thing I am going to do on my next trip with my new a7s3 rig is to shoot in S-Log so I have more control with color grading. I have not done that till now because I have been using a sony a6300 with only 8 bit color.
This guy on YouTube is doing exceptional work without any blue filters, he says.. Which I find incredible.. But take a look and read the comments below it.
I'll post some more when I figure out a good work flow. Good luck!
Blake