1. Introduction
Marine fish culture in Mexico is still at an experimental level. Spotted sand bass Paralabrax maculatofasciatus has been identified, among other fish, as a potential
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candidate for aquaculture Matus-Nivon et al., 1990 . The distribution of this species
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ranges from Monterey Bay, USA to Mazatlan, Sinaloa, Mexico Miller and Lea, 1972 . Ž
It inhabits shallow waters up to 60 m in northwest Mexico Thomson et al., 1987; .
Lluch-Cota, 1995 , and is eurythermal because it tolerates temperatures from 7.58C to Ž
. 328C Thomson et al., 1987 . Spotted sand bass is carnivorous, preying mainly during
daytime on small crustaceans, bivalves, gastropods, cephalopods, ophiuroids, and fish Ž
. Ferry et al., 1997 . This Serranid species shows adaptability to culture conditions and
low territoriality. Sexual maturation and artificial propagation have been successfully Ž
. done Rosales-Velazquez, 1997 . The spotted sand bass can reach about 45-cm total
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length Van der Heiden, 1985 , and its white meat is of excellent quality; however, very little information is available on its nutritional requirements. Protein is the most
expensive component in fish feeds; hence, optimizing dietary concentrations is essential to minimize feed cost and to formulate feeds, which allow good growth and protein
utilization. The dietary protein level needed for maximum growth of carnivorous species
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under culture conditions has been reported to vary from 40 to 55 Tucker, 1998 . The only information available on the nutritional requirements of spotted sand bass
juveniles indicate those at 2.5-g mean weight need at least 55 dietary protein for best growth when casein is the sole protein source. However, in terms of feed conversion
Ž ratio apparently the requirement could be lower Anguas-Velez, personal communica-
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. tion . We need to determine the requirements for each species and for each stage of
development to produce appropriate practical diets. In the present study, the effect of the dietary protein level on growth and body composition of spotted sand bass juveniles fed
practical diets was evaluated.
2. Materials and methods
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