Taxonomy & naming
Brachygobius xanthomelas was described by Herre in Herre & Myers (1937) and is listed as valid by the Catalog of Fishes, which gives the type locality as freshwater ditches in the Mawai District of Johor, Malaysia. It is one of several similar banded Brachygobius, a genus in which species limits have long been confused in the aquarium trade.
Morphology
As in other Brachygobius, the body is stocky with a blunt head, and the pattern is dark bands on a yellow to golden ground. The pelvic fins are fused into a sucker disc. FishBase gives a maximum of 1 in SL. The fine pattern details that separate this species from its relatives have not been set out in the sources used here.
Habitat
The type locality indicates slow freshwater ditches. FishBase lists the species as freshwater and demersal, with a range covering Malaysia and Indonesia. Bumblebee gobies as a group live in still to slow water, including coastal swamps, ditches and the lower parts of rivers, and several tolerate brackish conditions. Measured water chemistry has not been published for this species.
Feeding
Brachygobius gobies are small predators that take tiny live invertebrates from the bottom and from plants. The wild diet of this species has not been described, so the genus pattern is the best guide.
Mating
Species in the genus are cave spawners: the pair uses a small cavity, and the male cleans it and guards the eggs. Behaviour of this species specifically has not been described.
Breeding
In other Brachygobius, the female lays adhesive eggs on the roof or wall of a cavity and the male fans and guards them until hatching. This has not been described for B. xanthomelas, and nothing is published on rearing its fry.
In the aquarium
Bumblebee gobies generally do best in small, calm, well-planted tanks with hiding places such as short lengths of pipe or shells, and many keepers add a little salt for the group. Many refuse dry foods and need live or frozen small foods. Guidance specific to this species has not been published, and the trade name should not be taken as proof of identity.
Conservation
The IUCN assessed Brachygobius xanthomelas as Data Deficient in 2018, which means there is too little information to judge its extinction risk. The type locality lies in a part of the Malay Peninsula where lowland ditches and swamps have been heavily modified.