This study surveyed and analyzed samples of aquatic insects at 10 pondst Binh Hung Hoa biological system on March and August in 2015. The results recorded 31 species belonging to 24 families, 6 orders, include Coleoptera, Diptera, Odonata, Hemiptera, Ephemeroptera and Trichoptera. In particular, the larvae of theory derdiptera had the best diversity of composition, wise distribution and high density. However, the larvae of t h e order ephemeroptera and order trichoptera had the least diversity and low level of density and distribution at maturation ponds. Among ponds, the diversity and density of aerobic pond and sedimentation pond were high while the maturation ponds were low. The composition of aquatic insects had high similarity in the same function ponds and low similarity in the different function ponds. The species composition diversity and abundance of aquatic insects were the highest in the sedimentation pond and lowest in the other ponds. In the rainy season, the species composition diversity of aquatic insects were higher than those in the dry season.

In a total of four surveys at eight sites in some major rivers in Vinh Long province during 2013 to 2014, 18 species of cladoceran, belonging to 14 genera, 7 families and 2 orders, were recorded. The cladocerans fauna in Vinh Long province is recognized as moderate diverse, and the species recorded were mostly common species. Among 18 species, Grimaldina brazzai Richard, 1892 is a rare species. A total of four females specimens of species G. brazzai were collected at the Co Chien river, but male specimens were absent. The specimens were morphologically identified as G. brazzai described first by Richard (1892), followed by Brook (1959), Idris (1983), Smirnov (1992) and Hollwedel (2003). Grimaldina brazzai is currently the only one species in the genus Grimaldina and has been recorded in several tropical countries, such as Brazil, Thailand, Laos, Philippines, Indonesia, Malaysia, Cambodia and Singapore. They occur in lakes and rice fields, but population of this species is very limited in nature. In Vietnam, this species was first recorded in South Vietnam by Shirota (1966), but has not been described since then until recently Sinev & Korovchinsky (2013) recorded this species in the Cat Tien National Park, Dong Nai province, South Vietnam.

Cladocera is investigated in waterbodies of Vinh Long province during 2013 to 2014. Samples were collected from eight stations. 18 cladocera species belonging to 14 genus, 7 family, 2 order and 1 class were observed. In that, 14 species were recorded in 2013, and 15 species were recorded in 2014. The species composition of order Anomopoda always dominates in waterbodies. The species Grimaldina brazzai Richard, 1892 (Macrotricidae, Anomopoda, Branchiopoda) are redescribed from material collected in Co Chien river of Vinh Long province in 2013. The results have identified 04 female individuals, but no male individuals of G. brazzai are recorded. Morphological characteristics of G. brazzai are as descriptive as Richard (1892), Brook (1956) and Idris (1983). Morphological characteristics of Grimaldina và G. brazzai female are described and illustrated details by Optikam and Adobe Illustrator CS5. Some morphology characters used to identify, e.g., eye, head pores, Labral plate, Antennule I - II, postabdomen. The genus Grimaldina comprises only one species G. brazzai. This species has been recorded in lakes and rice fields of Brazil, Thailan, Lao, Philippines, Indonesia, Malaysia, Cambodia and Singapore, rare species. The first time in Vietnam Shirota (1966) was recorded this species in South Vietnam, but he has not describe.

In a total of four surveys at eight sites in some major rivers in Vinh Long province during 2013 to 2014, 18 species of cladoceran, belonging to 14 genera, 7 families and 2 orders, were recorded. The cladocerans fauna in Vinh Long province is recognized as moderate diverse, and the species recorded were mostly common species. Among 18 species, Grimaldina brazzai Richard, 1892 is a rare species. A total of four females specimens of species G. brazzai were collected at the Co Chien river, but male specimens were absent. The specimens were morphologically identified as G. brazzai described first by Richard (1892), followed by Brook (1959), Idris (1983), Smirnov (1992) and Hollwedel (2003). Grimaldina brazzai is currently the only one species in the genus Grimaldina and has been recorded in several tropical countries, such as Brazil, Thailand, Laos, Philippines, Indonesia, Malaysia, Cambodia and Singapore. They occur in lakes and rice fields, but population of this species is very limited in nature. In Vietnam, this species was first recorded in South Vietnam by Shirota (1966), but has not been described since then until recently Sinev & Korovchinsky (2013) recorded this species in the Cat Tien National Park, Dong Nai province, South Vietnam.