The biosynthesis of astaxanthin in the prawn was studied further using pure carotenoids and preparations obtained from natural sources. Zeaxanthin, obtained from the Chinese lantern, was fed to the prawn, Penaeus japonicus Bate. Astaxanthin was biosynthesized from zeaxanthin, thus indicating the existence of a second pathway to astaxanthin in the prawn. Canthaxanthin and astaxanthin from crab waste were respectively metabolized, too, and absorbed as body astaxanthin in the prawn. Pigmented preparations from corn gluten, alfalfa, and Spirulina (blue-green alga) were found to increase the body astaxanthin to various degrees.