Among the proposed functions of carotenoids in aquaculture have been those of pigmentation, antioxidant functions, as a source of pro‐vitamin A, cellular protection from photodynamic damage, enhancement of growth and reproductive potential. However results reported by various authors are often contradictory. Some evidence suggests that these pigments may perform vital roles in growth and reproductive success in Crustaceans. Additional efforts need to be devoted to the understanding of the active forms of the carotenoid derived metabolites, retinoids in crustaceans. Dietary carotenoids are the sole biological precursors of retinoids in crustaceans. The importance of carotenoids as bioactive molecules reside to a large degree on their conversion to retinoids that are involved in the activation of hormonal nuclear receptors. Retinoids play a prominent role in many developmental processes, including embryonic development and differentiation of various cell types. The presence of receptors of retinoic acid in crustaceans and our findings of retinoids in the neuroendocrine complex and in reproductive tissue, as well as the enhancement of the ovarian development in shrimp suggests an important role of these metabolites in shrimp physiology for their successful aquaculture.

Functional feed supplemented with alternative-economic nutrient sources (protein, carbohydrates, lipids) and probiotics are being considered in shrimp/fish aquaculture production systems as an option to increase yield and profits and to reduce water pollution. In this study the probiotic potential to formulate functional feeds have been evaluated using four dietary treatments: Treatment 1 (B + Bs); Bacillus subtilis potential probiotic strain was supplemented to a soybeanmeal (SBM)—carbohydrates (CHO) basal feed. Treatment 2 (B + Bm); Bacillus megaterium potential probiotic strain was supplemented to the same SBM-CHO basal feed. In Treatment 3 (B); SBM-CHO basal feed was not supplemented with probiotic strains. Treatment 4 (C); fishmeal commercial feed (FM) was utilized as positive control. Feeding trials evaluated the survival, growth, and food conversion ratio and stress tolerance of juvenile Litopenaeus vannamei (Boone) Pacific white shrimp. Best overall shrimp performance was observed for animals fed with Treatment 1 (B+Bs); additionally, stress tolerance and hemolymph metabolites also showed the best performance in this treatment. SBM-CHO basal feed not supplemented with probiotic strains (B) presented smaller growth and lower feed conversion ratio (FCR). Shrimps fed with the fishmeal commercial feed (C) presented the lowest stress tolerance to high ammonia and low oxygen levels. Specifically selected B. subtilis strains are recommended to formulate functional and economical feeds containing high levels of vegetable; protein and carbohydrates as main dietary sources in L. vannamei cultures.

Background: Dunaliella salina is the most important species of the genus for β-carotene production. Several investigations have demonstrated that D. salina produces more than 10% dry weight of pigment and that the species grows in salt saturated lagoons. High plasticity in the green stage and the almost indistinguishable differences in the red phase make identification and differentiation of species and ecotypes very difficult and time consuming.

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