This study evaluated the nutritional potential of three seaweed extracts (Ulva lactuca, Eisenia sp. and Porphyra sp.) as possible ingredients in shrimp feed to improve growth and main digestive enzyme activities. Seaweed extracts were included in replacement of wheat and soybean meal in isoproteic diets (35 +/- 0.5%) at three levels of inclusion (5, 10, and 15%) and tested during 28days in a feeding trial on Litopenaeus vannamei (initial weight 1.15 +/- 0.08g). Growth performance and feed utilisation parameters, in addition to trypsin, chymotrypsin, lipase and amylase activities, were evaluated. An increase of ash content in experimental diets was observed as seaweed extract inclusion level increased (from 7 up to 13.4%). All shrimps fed with seaweed diets significantly improved (p<0.01) final weight (FW), weight gain (WG), specific growth rate (SGR) and feed intake (FI) in contrast to control diet. In general, Ulva diets presented the best shrimp growth performance, among which inclusion of 15% Ulva extract resulted in significantly higher FW, WG and SGR (p<0.01) compared to control, Porphyra and Eisenia diets. In the case of chymotrypsin, lipase and amylase enzyme activity, a significant interaction between seaweed type and inclusion level was found (p<0.01), where in most cases, inclusion level of 5% of all type of seaweed resulted in an increase of the enzyme activities. The use of any of the three proposed seaweed extracts in balanced feed, especially Ulva, is suggested to promote shrimp growth productivity.