In the genus Brachygobius we find some of the smallest freshwater goby species. One of these dwarfs is B. mekongensis, a species that was only scientifically described in 2000. The late scientific recording of this species, which is widely distributed in the Mekong River basin in Laos, Cambodia and Thailand, is due to the fact that it was previously regarded either as a juvenile of another species or as an eastern population of the Indian dwarf species B. nunus.
At less than 2 cm in length, B. mekongensis is fully grown. The females are somewhat larger and fuller than the males. There is even a breeding report on the animals from 1990, although H. Horsthemke incorrectly identified them as B. aggregatus – forgivable, as the species B. mekongensis had not yet been described at the time. According to him, B. mekongensis spawns on hard substrate (i.e. not in caves, like many other Brachygobius species). The approx. 30 eggs are guarded by the male until hatching.
B. mekongensis is a pure freshwater species, there are no reports from brackish water. In the wild, it prefers waters with abundant underwater vegetation, e.g. Vallisneria. The water depth is usually 0.3-1.5 m. The dwarf fish species Boraras micros and Indostomus spinosus, which are also occasionally encountered in the hobby, live together with it.
In the aquarium, the dwarf gobies are best fed with small live food. If the rain barrel or pond does not provide enough food, grindal worms, chopped tubifex and Artemia nauplii are a good substitute. B. mekongensis are not demanding in terms of hardness and pH value; any drinking water is suitable for maintenance and breeding. The temperature can be between 22 and 28°C.
For our customers: the animals have code 407152 on our stock list. Please note that we only supply the wholesale trade.
Text & photos: Frank Schäfer
