The objective was to evaluate the use of green alga Ulva lactuca in the growth of fingerlings sea chub Girella laevifrons. Three experimental diets were used with inclusion levels of 15, 30 and 45% U. lactuca meal and a control diet without inclusion of U. lactuca meal (0%). The trial lasted 30 days and was carried out in duplicate groups and 120 fingerlings of average weight of 0.458 ± 0.10 g were used, which were distributed in 8 glass tanks at a rate of 15 specimens per aquarium. The highest growth in weight and length was obtained with 30% inclusion of U. lactuca meal, significantly different (p < 0.05) from the treatment with 15% inclusion of U. lactuca meal. This is the first work where the use of the macroalga U. lactuca has been investigated in the growth of this species and therefore it is recommended to perform more similar work in order to determine the aquaculture potential that it would have.