Dichotomyctere is a genus of small pufferfish in family Tetraodontidae, found across South and Southeast Asia in India, Bangladesh, Myanmar, Sri Lanka, Thailand, Malaysia, Indonesia and Brunei. The atlas's 3 species - the topaz puffer (D. fluviatilis), green spotted puffer (D. nigroviridis) and figure-eight puffer (D. ocellatus) - range 3–8 in and were formerly classified in the much larger genus Tetraodon before taxonomic revision split them out. Like other tetraodontid puffers, they have a beak-like structure of fused teeth that grows continuously and must be worn down on hard-shelled prey such as snails, and they can inflate by gulping water when threatened.
The green spotted puffer is by far the best-known species in the genus and a long-standing aquarium staple, prized for its bold yellow-green, black-spotted pattern and notably inquisitive behavior - but it is also one of the hobby's most persistent sources of husbandry confusion, since juveniles are typically sold from freshwater tanks even though the species is euryhaline and needs increasing salinity toward full marine strength as it matures. The figure-eight puffer stays in brackish water throughout its life and remains smaller and generally more tolerant of community-style setups, while the topaz puffer is less commonly traded. All three species tend toward territorial, often aggressive behavior and are best kept alone or with carefully chosen tankmates. Conservation status is Least Concern for two species and Data Deficient for the third.