Dunalliella salina and Isochrysis sp showed a greater influence on reproductive value of the rotifer Brachionus sp “Alvarado” strain, associated to higher lipid, carbohydrate, protein and pigment content. These results contribute to improve knowledge on the optimal culture conditions for this tropical rotifer. We analyzed toxic and trace elements in carp from fish ponds. Fish liver was the main target organ for accumulation of Cu, Se and Zn, and dorsal muscle for Sr and Li. Fish liver showed a decrease of a range of elements towards the end of season. Arsenic was uniformly distributed in fish organs showing potential to build up in edible parts.