The green seaweeds (gut weed, Enteromorpha spp. and genus belonging to Cladophoraceae) can be found commonly in brackish water bodies in the Mekong delta. Their highest standing crop and natural productivities were in the ranges of 2.5-3.9 kg/m² and 11.9-27.2 ton ww/ha, respectively. These seaweeds contain valuable amino acids and fatty acids, including omega-3 and omega-6 polyunsaturated fatty acids that can be used as feeds for aquaculture species. Several feeding trials indicated that growth performance of herbivorous fish (Scatophagus argus, Osphronemus goramy and Oreochromis niloticus) in the alternative feeding regimes between commercial pellet feed and green seaweeds were comparable to the control group fed single commercial feed as well as feed conversion ratio could be reduced by 26.1–57.8%. Moreover, green seaweed protein could substitute up to level of 40% of fishmeal protein in practical diets for these species that have no adverse effects on growth, feed utilization and quality of fish. For shrimp Litopeneaus vannamei and Penaeus monodon, green seaweeds could be used in co-culture that help to reduce about 50% feed supply as well as maintain better water quality in the culture medium. Besides, green seaweed meal could replace 60% of soybean meal protein in shrimp diets. However, more comprehensive research is needed to optimize the use of green seaweed as a promising alternative feed that could contribute to the sustainable development of aquaculture in the Mekong delta.