Astaxanthin for color enhancing red fish, is it benign?

[Wharf]

I know this is technically another food thread, apologies in advance. I usually gravitate to red and yellow fish d/t having beaming blue backgrounds (can be mitigated slightly with lighting after taking suggestion from members). Red and yellow color fish actually pop with this type of background. Whenever I kept Tropheus I always had a blue background.

With that in mind, my question is there are tons of color enhancing foods with Astaxanthin or Marigold in them as an ingredient or component of the food. Is Astaxanthinaa benign or relatively safe for a fish's health on a long term basis? Is it as harmless as say Spirulina for yellow and blue fish? I just wanted to know the MFK Sempai's thoughts and input on the matter

 

[neutrino]

Not just benign, it has benefits besides color.
https://onlinelibrary.wiley.com/doi/abs/10.1111/raq.12200

Comes not just from the sources we typically think of, such as shrimp, salmon, etc., sources of astaxanthin include various algae. (like the green algae Haematococcus pluvialis in NLS Algaemax)

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7333709/

Astaxanthin is the reddish carotenoid pigment that gives color to shrimp, salmon, and flamingo. However, these animals do not synthesize astaxanthin by themselves. Instead, microalgae are the initial producers of astaxanthin in nature. Because of its strong antioxidant activity and potential benefits for human health, astaxanthin has high commercial value in the nutraceutical, cosmetic, and feed industries. Haematococcus pluvialis is a well-studied alga with the highest known level of astaxanthin accumulation and thus is widely used as an industrial source for natural astaxanthin production. In recent years, Chromochloris zofingiensis has emerged as a promising producer because of its ability to synthesize astaxanthin and its better growth robustness than H. pluvialis.

There are other carotenoids with nutritional benefits. Spirulina has several such caraotenoids among its other pigmented nutrients. Not to make a plug for spirulina over other foods, but while astaxanthin gets a lot of attention these days, it's really one among a number of beneficial pigmented nutrients that several high quality fish foods have by virtue of their ingredients (or sometimes as added supplements), meaning I don't find it necessary to add to what's already in the foods I use.