Doolan BJ, Booth MA, Allan GL & Jones P (2009) Effects of dietary astaxanthin concentration and feeding period on the skin pigmentation of Australian snapper Pagrus auratus (Bloch & Schneider, 1801). Aquaculture Research 40: 60-68. 

Available online: http://dx.doi.org/10.1111/j.1365-2109.2008.02063.x 

Summary

Small scale production of snapper Pagrus auratus has occurred in sea cages in Australia in recent years however farmed snapper typically display a dull grey appearance and lack the pink skin pigmentation of wild snapper. Farmed snapper are generally sold to wholesale and retail markets whole rather than as fillets and subsequently, market value and consumer acceptance are negatively affected due to this uncharacteristic skin colour. In order to change the skin of snapper pink prior to harvest, a pigment known as astaxanthin can be added to feeds. Astaxanthin is an expensive feed additive therefore it is important to establish the optimal dose rate and feeding duration required to improve pigmentation.

In this study, groups of snapper were fed one of seven diets containing astaxanthin at concentrations ranging from 0 to 78 mg kg-1 for 63 days. The skin colour of all fish was measured with a colour reader at days 0, 21, 42 and 63. Snapper fed astaxanthin diets became pinker than snapper fed no added astaxanthin after 21 days. A greater level of pinkness was achieved after 42 days of feeding with no differences in the skin colour of fish fed diets containing between 39 and 78 mg kg-1. There was no further improvement in skin colour after feeding these diets for an additional 21 days. The results suggest that cultured snapper should be fed diets containing 39 mg kg-1 astaxanthin or greater for at least 42 days prior to sale to improve pink colouration.