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Morphological development, allometric growth and behaviour of hatchery-reared California halibut Paralichthys californicus were studied from hatching to metamorphosis (42 days post hatch, dph) at 18 C. Mean standard length (L S ) of larvae and juveniles increased from 2·1 mm at hatching to 10·5 mm at metamorphosis with the increase in length being approximately linear. Stages of morphological development were described using the alphabetic staging (A-I) used for other flatfish species. Organogenesis and differentiation were more rapid and complex in yolk-sac (hatching, stage A-3 dph, stage B), preflexion (3-19 dph, stages B-C), and flexion larvae (from 20 to 23 dph, stages D-E), as larvae developed most of their sensory, feeding, respiratory and swimming systems. After notochord flexion at 24-25 dph (stage F), most morphological changes were related to the progressive transformation from a bilateral symmetrical larva to an asymmetrical benthic juvenile (42 dph, stages G-I).

The red yeast Phaffia rhodozyma contains astaxanthin as its principal carotenoid pigment. Incorporation of this yeast into the diet (15% wt/wt) of rainbow trout induced pigmentation within 43 days. However, lobsters fed the same diet did not readily accumulate the carotenoids of the yeast, though they became pigmented on a diet of live brine shrimp. The primary pigment isolated from the bodies of trout and lobsters fed the red yeast was astaxanthin. We conclude that P. rhodozyma is an excellent source of astaxanthin for cultivated salmonids. Key words: astaxanthin, carotenoid, diet, lobster, Phaffia rhodozyma, salmonids, yeast

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