Canthaxanthin and astaxanthin levels in farmed rainbow trout over 56 days
What it found
In farmed rainbow trout, canthaxanthin built up to 1.21 mg per kg of muscle after 42 days.
Eating average amounts of this trout would give a person about 0.53 mg of canthaxanthin each week.
What they found
Animal and lab studies
Colorant buildup in trout
After 42 days, canthaxanthin reached 1.21 mg per kg of muscle, with readings varying by about 0.06 mg. Astaxanthin reached 3.70 mg per kg, varying by about 0.04 mg. Both were below legal limits.
Flesh color in trout
All treated groups developed the expected pink or red flesh color. Color tests showed no meaningful differences between the feeding plans.
Growth in trout
Fish given the colorants grew at about the same rate as fish on plain feed. No harmful effects were seen in the animals at the doses used.
Feeding schedule in trout
Giving the colorants once a day or twice a day made no difference to how much astaxanthin built up in the fish muscle.
Other findings
Weekly intake for people
Based on average Italian fish eating habits of 441 g per week, a person would take in about 0.53 mg of canthaxanthin weekly. For a 75 kg person, that daily amount is well below the accepted limit of 0.003 mg.
What the authors conclude
- They conclude that canthaxanthin and astaxanthin levels in all trout samples stayed within legal limits.
- The authors note that stopping treatment after 42 days could lower farming costs without losing color.
- They suggest that eating farmed trout adds some carotenoids to the human diet, though not enough on its own to match supplement doses.
How it was done
Farmers add these colorants to fish feed to give salmon and trout flesh the pink shade shoppers expect. The authors wanted to measure how much of each colorant stays in the fish and how much a person might take in by eating it.
They fed 480 rainbow trout different mixes of astaxanthin and canthaxanthin for 56 days. Every 14 days they tested five fish from each tank to check growth, flesh color, and colorant levels in the muscle.
What it can’t tell you
- This work measured colorant levels in fish, so it cannot show direct health effects in people who eat them.
- Estimates of human intake rely on average fish consumption figures rather than tracking actual diets.
The paper
- Title
- Astaxanthin and canthaxanthin (xanthophyll) as supplements in rainbow trout diet: in vivo assessment of residual levels and contributions to human health
- Type
- Study
- Evidence
- Animals and lab studies
- Summarised from
- Full text
- Cite
- Brizio P, Benedetto A, Righetti M, et al (2013). Astaxanthin and canthaxanthin (xanthophyll) as supplements in rainbow trout diet: in vivo assessment of residual levels and contributions to human health. Journal of agricultural and food chemistry. doi:10.1021/jf4012664Free full textPubMed 24156372DOI
Summary written 30 Sep 2026. Check it against the paper before it changes what you eat. How we summarise papers · Report an error