Brachygobius xanthomelas HERRE, 1937

Classification

Order: Perciformes Family: Gobiidae

Distribution

Type locality is ’55 miles north of Singapore, freshwater ditches, Mawai District, Johore, Malaysia’, and this species has been recorded throughout much of Peninsular Malaysia and southern Thailand.

It’s also been recorded on Bangka Island, Indonesia, but we’ve been unable to confirm if it occurs on neighbouring Sumatra.

Records from the Kapuas River in Indonesia (Borneo), Cambodia, and Singapore appear to be in error, although it may have been extirpated from the latter, and as with most members of the genus a degree of confusion surrounds its identity (see ‘Notes’).

Habitat

Generally restricted to lowland environments including freshwater swamps, streams, minor tributaries, and forest peat swamps. Marginal vegetation tends to grow thickly with beds of aquatic plants from genera such as Cryptocoryne or Barcalaya and patches of submerged leaf litter found in some places.

Peat swamp habitats are characterised by tannin-stained, tea-coloured water, very low acidity, minimal conductivity, and negligible hardness. Substrates are composed of mud and peat with overlying leaf litter and submerged woody structures such as tree roots.

Unlike most congeners this species does not appear to occur in tidal or otherwise brackish environments.

Maximum Standard Length

15 – 20 mm.

Aquarium SizeTop ↑

Base dimensions of 45 ∗ 30 cm or equivalent should be the minimum considered.

Maintenance

Provide plenty of hiding places and cover, the idea being to create broken lines of sight to allow weaker individuals to escape continual attention from dominant fish.

Crushed coral or coral sand can be mixed into the substrate to act as a buffer if necessary, or marine salt added at a dose of around 2 grams per litre.

Filtration should not be strong with an air-powered sponge-type unit ideal.

Water Conditions

Temperature: 22 – 28 °C

pH: 7.0 – 8.5

Hardness: 143 – 357 ppm

Diet

Small live foods such as Artemia, Daphnia, etc., should be considered essential although some specimens will learn to accept  frozen alternatives. Dried products are normally ignored.

Behaviour and CompatibilityTop ↑

Does not make an ideal community fish and best kept in a species-specific set-up.

Although males in particular are territorial towards one another a group of 6 or more should be the minimum purchase since when such numbers are present aggression is spread between individuals plus the fish are bolder and exhibit more natural behaviour.

Sexual Dimorphism

Sexually mature females often appear rounder-bodied than males, particularly when gravid.

NotesTop ↑

This species is occasionally available in the aquarium trade, though often misidentified, and its name has also been widely misapplied to an unidentified member of the genus which does not correspond to any of the described species.

The latter is the fish depicted in most online images and it possesses a dark marking on the anterior base of the first dorsal-fin, while the same area is colourless in B. xanthomelas.

According to current knowledge it can be diagnosed as follows: <30 lateral scales; one black band reaching mid-ventral line posterior to anal-fin; first black trunk band ending at dorsal-fin origin; no predorsal or opercular scales; basal part of first dorsal-fin not black anteriorly.

Brachygobius currently contains 9 described species, and although all are referred to collectively as ‘bumblebee’ gobies only B. doriae and B. sabanus are commonly-available  in the ornamental trade.

The majority should only be considered nominal taxa for the time being since the genus  appears to be considerably more diverse than currently-recognised. Therefore, although we’ve assigned images to profiles based on how well they match the key of Inger (1958) the identification of most can only be thought of as tentative pending publication of a forthcoming review.

The grouping is often included in the subfamily Gobionellinae alongside genera such as Chlamydogobius, Mugilogobius, Pseudogobiopsis, Rhinogobius, Schismatogobius, and Stigmatogobius.

It’s considered most closely-related to the genus Pandaka with the two sharing numerous characters but differing in the morphology of the head lateral line system and number of epurals present.

References

1. Herre, A. W. C. T. and G. S. Myers, 1937 - Bulletin of the Raffles Museum No. 13: 5-75
   A contribution to the ichthyology of the Malay Peninsula.
2. Inger, R. F., 1958 - Fieldiana Zoology 39(14): 107-117
   Notes on the fishes of the genus Brachygobius.
3. Larson, H. K., Z. Jaafar, and K. K. P. Lim, 2008 - The Raffles Bulletin of Zoology 56(1): 135-155
   An annotated checklist of the gobioid fishes of Singapore.
4. Miller, P. J., 1989 - Cybium 13(4): 375-383
   The classification of bumble-bee gobies (Brachygobius and associated genera) (Teleostei: Gobiidae).
5. Ng, H. H. and H.-H. Tan, 1999 - Zoological Studies 38(3): 350-366
   The fishes of the Endau drainage, Peninsular Malaysia with descriptions of two new species of catfishes (Teleostei: Akysidae, Bagridae).