There are some great feeds on the market containing color enhancers such as Astaxanthin and Beta Carotene. TDO sold by Reed Mariculture was recently tested in a study about the effects of Astaxanthin on larval clownfish. You can read about it here:
https://reedmariculture.com/docs/RMI-Executive-Summary-of-Clownfish-Astaxanthin-Study-2017.pdf
The formula of their food was changed from 200PPM to 400PPM after the findings. TDO is a staple food for many clownfish breeders and folks in aquaculture. (As a disclaimer we are a wholesale distributor of this product, but it's worth a mention that all the customer feedback we have received has been good.)
Back in 2013 we started adding dried D. salina powder to our foods which is standardized for beta carotene. That's why
LRS foods are tinted orange. There is a history of that algae being used as a feed supplement in aquaculture with good results. A few years later when we developed our "Fertility Frenzy" food for the aquaculture community we added Astaxanthin powder and D. salina to the formula. Clownfish breeders were our initial test market and the feedback was that the food did create larger clutches of eggs, and more vibrant broodstock and juveniles. There a bunch of links and videos about it here:
http://www.larrysreefservices.com/testimonials.html
Currently, The Oceanic Institute of Hawaii, University of Florida, and Biota are the biggest consumers of that product on a continuous basis. I firmly believe that quality feeds with pigmentation enhancers can improve the coloration of marine fish. The study above by Virginia Tech seems to indicate that as well.