Correction of black tiger prawn (Penaeus monodon fabricius) coloration by astaxanthin

After two months of feeding a group of juvenile black tiger prawn (Penaeus monodon) with a commercial feed (CF), their external pigmentation changed from its normal greenish-brown to a light blue. This condition was thought to be induced by a carotenoid deficiency in the feed. Nutritional improvement and hence correction of this condition was attempted by adding 50 ppm astaxanthin (Roche Ltd^®) into one feed (AF) and 5% addition of brown algae (Chnoospora minima) into a second feed (BF). After four weeks of feeding, the prawns fed on AF reverted to their normal greenish-brown pigmentation. The carotenoids present in the BF feed increased carotenoid content in the prawns, but the levels were not high enough to correct the blue coloration. Analysis of carotenoid content in the shells of the groups showed 318%, 57% and 14% increase for AF, BF, and CF respectively, with 70–90% of the total carotenoid being in the form of astaxanthin. Deposition of astaxanthin was higher in the shell than in the flesh, with deposition in the flesh plateauing after two weeks, whilst deposition in the shell increased steadily.

The importance of these findings to the marketing of cultured shrimps is discussed.