The eect of three carotenoid sources on growth and pigmentation of juvenile freshwater crayfish Cherax quadricarinatus SHEENAN HARPAZ Department of Aquaculture, Agricultural Research Organization, Bet Dagan, Israel MOSHE RISE & SHOSHANA (MALIS) ARAD The Institutes for Applied Research, Ben-Gurion University of the Negev, Beer-Sheva, Israel NATAN GUR Zemach Central Feed Mill, M.P. Jordan Valley, Israel Abstract The eect of adding carotenoids from various sources to feed of juvenile freshwater crayfish Cherax quadricarinatus on pigmentation, growth and survival was examined under laboratory conditions. Juvenile crayfish were fed diets fortified with carotenoids at a level of 100 lgg )1 for a period of either 49 or 55 days. Carotenoid sources were: dried algal cells prepared from Dunaliella salina in which the main carotenoid is b-carotene; a synthetic carotenoid, astaxanthin (Carophyll Pink 8%, manufactured by Ho- man–La Roche) and alfalfa meal. Crayfish receiving feeds fortified with carotenoids exhibited better body colouration than those in the control group, which were fed a diet to which no carotenoids were added. Growth and survival of the crayfish were not aected by the addition of carotenoids to their diet. KEY WORDS: KEY WORDS: carotenoids, Cherax quadricarinatus, crayfish, microalgae, pigmentation Received 14 July 1997, accepted 5 March 1998 Correspondence: Sheenan Harpaz, Department of Aquaculture, Agricul- tural Research Organization, P. O. Box 6, Bet Dagan, 50250, Israel (E-mail: harpaz@agri.huji.ac.il) Introduction The culture of Cherax quadricarinatus in a temperate climate is carried out in two stages. In the first stage the newly hatched crayfish are nursed in tanks under protected indoor conditions for 2–3 months during the cold months of the year and juveniles are then stocked in ponds for growout during the warmer months of the year (Karplus et al. 1995; Sagi et al. 1997). One of the problems in using this system is the body colouration of the juveniles which is reflected in a high proportion of pale coloured juveniles. Potential farmers relate negatively to these (otherwise healthy) juveniles. This phenomenon has also been noted by Sommer et al. (1991) who stated that the ability to market adult crustaceans is usually dependent on the level of their colouration. Feeding cultured crustaceans with pelleted diets usually leads to inadequate pigmentation (Huner & Meyers 1979). Caroten- oids, which are the main pigment source for these crustaceans are not usually added to the pelleted feeds and the high density in which the cultured crustaceans are reared tends to exhaust the natural pigment sources in the environment. The loss of pigments can be overcome by their addition to the artificial diet. Both artificial and natural pigment sources have been utilized in the past (Negre-Sadargues et al. 1993). A number of studies have addressed this issue and have evaluated dierent potential pigment sources (Yamada et al. 1990; Chien & Jeng 1992). Dietary plant matter, which can also serve as a pigment source, has been shown to have beneficial eects on crustacean moulting and growth (Harpaz & Schmalbach 1986). Pigmentation in crustaceans results mainly from the accumulation of astaxanthin, free or esterified, in their integument (Katayama et al. 1972; Tanaka et al. 1976; Simpson et al. 1981; Sagi et al. 1995). Astaxanthin has also been identified in the eggs and eyestalks of crayfish, indicat- ing its possible roles in larval development and visual processes (Wolfe & Cornwell 1965). Astaxanthin and astaxanthin esters, together with small amounts of other keto-carotenoids, have been identified in the integumentary tissues of crayfish (Wolfe & Cornwell 1965). The plant carotenoids b-carotene and lutein have been found to be the predominant pigments in the internal organs, muscle and eggs of crayfish. 201 Aquaculture Nutrition 1998 4 ; 201^208 . ............................................................................................. . ............................................................................................. Ó 1998 Blackwell Science Ltd