Yes they work with brook trout from my experience especially in conjunction with spawning time when the colors on the male are naturally enhanced. It takes a couple of months though. It's designed to enhance the flesh colors for marketing, but it also enhances the external red based colors.
If I know I will be harvesting brook trout I will start feeding them the astaxanthin enhanced feed a few months before harvest.
Here's one that was fed the astaxanthin enhanced Aquamax feed for a few months. I think it's 5D09?
Vs. these two during spawning time a different year that were not:

Allegedly a little paprinka will enhance the reds in brook trout but I have no experience with it. I think it would be easier to just buy the enhanced feed (only a few bucks more) than messing with adding the paprika with oil etc.
I've used the color enhanced feed with largemouth bass, bluegill, and yellow perch and did not observe any changes.
Unfortunately I can't remember if I used the enhanced feed with my browns that I raised on different years than my brooks but here's one that has some really good color:
