Adults of three fairy shrimp species are present in Thailand from February through June in ephemeral waters (ponds, roadside canals, and rice field ditches) filled mostly by the rain. Branchinella thailandensis is of interest in aquaculture because it reproduces rapidly and has high nutritional value. However, no detailed studies on its reproductive biology are available. Anatomical analyses of male and female genitalia were studied with light microscopy and SEM. Shrimp were reared in the laboratory at 28 ± 1 °C in aerated, potable water using the alga Chlorella sp. as food. One female and two males were placed in each of ten 1-L observation containers and the female reproductive stages were monitored every hour over six days. Branchinella thailandensis exhibits zygogenetic reproduction and oviparity, where fertilization is direct and internal; the brood pouch shows an undifferentiated amplexial groove. Males and females reach maturity on days 7 and 8 after hatching, with a mean standard length of 10.3 and 12.2 mm, respectively. Males have unique spines on the gonopods, with a tip on a socket-like base; accessory glands were not evident in histological sections. Females have biramous ovaries; the shell glands are organized in two paired, bilateral clusters, in which the glandular unit is formed by two gland-cells and a single duct. After six complete reproductive cycles, the mean total duration of the reproductive cycle was ∼24.0 h (N = 60). The total duration of the reproductive cycle and egg production increased with age (subsequent reproductive cycles). No oösorption in unmated females was observed, and the oöcytes passed to the ovisac independent of copulation. Our results confirmed that Stage 3 is the longest reproductive stage in anostracan females. Branchinella thailandensis produces typical freshwater anostracan sculptured eggs, and belongs to the fairy shrimp group without a sub-cortical space beneath the egg shell.