Field surveys on the diversity of fishes were conducted in Ba Lat estuary and Xuan Thuy National in 2012 and 2013. The authors identified a total of of 122 species belonging to 13 orders and 46 families. In of species richness, Perciformes is the most diverse order with 68 recorded species (or 55.74 percent of the species number), followed by Clupeiformes with 17 species (or 13.93 percent) and Aulopiformes with 9 species (or 7.38 percent), others orders are represented by 1-4 percent of the total species number. The authors recorded 28 species with economic value, that can be used for food and aquarium porposes. Especially, three species were listed in the Vietnam Red Data Book (2007), including: Bostrychus sinensis (as critically endangered)
O.,anodon thrissa (as endangered), and Konosirus punctatus (as vulnerable). The authors also found two invasive species in this area, namely Oreochromis mossambicus and Oreochromis niloticus niloticus.