[5] As in all true Gobiidae, the ventral fins of Brachygobius nunus have fused into a suction cup that they use to attach to surfaces in nature and even to glass inside an aquarium.

Its natural habitat is saltwater swamps and stream estuaries in Borneo, India, Indonesia, Malaysia, Myanmar, Singapore, and Thailand.

[2][5][8] While B. nunus can often survive in a freshwater aquarium, brackish conditions (with at least two teaspoons of sea salt mix per gallon of water) are recommended.

[2] Live or frozen brine shrimp, daphnia and whiteworms are optimal foods.

One source says that placing a dozen juveniles B. nunus together in a 10-US-gallon (38 L) aquarium is a good way of successfully matching pairs for breeding.