Effect of food type on growth and survival of Chirostoma riojai Solοrzano y Lοpez, 1965 (Atheriniformes:Atherinopsidae) during early development GERARDO FIGUEROA-LUCERO1, MA. CECILIA HERNANDEZ-RUBIO1, OMAR R MEZA CONZΑLEZ1, JOSÉ LUIS ARREDONDO-FIGUEROA2, THALIA CASTRO BARRERA2, IRENE DE LOS ANGELES BARRIGA SOSA2 and ANTONIO RODRΙGUEZ CANTO2 1 Laboratorio de Hidrobiolog£a Experimental, Departamento de Zoolog£a, Escuela Nacional de Ciencias Biol½gicas. Instituto Politécnico Nacional. Prol. De M. Carpio y Plan de Ayala s/n. 11340. Mexico, D. F. 2 Universidad Aut½noma Metropolitana-Iztapalapa. Av. San Rafael Atlixco 186. 09340. Mexico, D. F.   Abstract The aim of the present study was to analyze the effect of the diet on growth and survival of Chirostoma riojai larvae, using a mixed feed until 30 days after hatching. The tested diets were: 1) Artemia nauplii, 2) Brachionus rubens, 3) formulated diet (micropellets in the size of a 65 μm rotifer, AZOO™, 50% protein), 4) Artemia nauplii + formulated diet, 5) Brachionus rubens + formulated diet, 6) Artemia nauplii + Brachionus rubens. Weight, total length, notochordal length and survival rate were determined for each diet. The optimal prey size for larvae from the first feeding up to 20 days after hatching was determined. The relative growth of the mouth opening was allometrically negative with respect to the width of the jaw and allometrically positive to notochordal length. Survival, notochordal and total length, as well as weight, were higher in those larvae fed with live feed. With the inert feed diet, larvae did not survive after the yolk-feeding period, probably due to the lack of enzymes in the digestive tract.   < back .