Reduction of malpigmentation rates in intensive larviculture of California halibut (Paralichthys californicus)

Malpigmentation is a common phenomenon in flatfish culture. We describe a stepwise series of three experiments aimed at reducing pseudoalbinism and ambicoloration in cultured California halibut (Paralichthys californicus). Pigmentation was assessed between 49 and 56 days post hatch when reared at 18-19 degrees C. Manipulation of rotifer enrichments was tested initially to reduce malpigmentation, with up to 10.8 +/- 3.8% of fish being normally pigmented. Dietary timing was subsequently examined, with late introduction of Artemia yielding the highest rate of normal pigmentation (40.6 +/- 8.6%) and eliminating ambicoloration. Rearing temperature was further shown to influence malpigmentation, with the most normally-pigmented fish occurring at 15 degrees C (46.3 +/- 2.7%) and the fewest at 23 degrees C (5.7 +/- 1.0%). Continued efforts to eliminate malpigmentation, in particular pseu-doalbinism, during intensive larviculture of California halibut will focus on additional modifications of key nutritional and environmental parameters.