Brachygobius nunus

Type locality is the 'river below Calcutta' which corresponds to the western side of the Ganges River delta south of Kolkata, West Bengal state, with reports as to its wider distribution varying significantly.

It's sometimes said to be present throughout India plus both mainland and maritime southeast Asia, but is more likely restricted to India, Bangladesh, Sri Lanka, and possibly Myanmar.

Inhabits both fresh and brackish water, and generally restricted to lowland, coastal environments including mangrove swamps, estuaries, and tidal streams.

Substrates thus tend to be composed of mud, sand and silt with overlying organic material such as leaf litter, mangrove roots, and submerged driftwood.

Base dimensions of 45 ∗ 30 cm18 ∗ 12 in or equivalent should be the minimum considered.

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.

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.

Unlikely to make an ideal community fish and should do best 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.

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

B. nunus is not particularly common in the international aquarium trade but its name is widely misapplied to other species such as B. doriae or B. sabanus which may give a false impression as to its availability.

It actually looks completely different to those two species and can be diagnosed as follows: <30 lateral scales; four black bands on the body; two black body bands reaching ventral midline posterior to anal-fin; a black stripe passing through the eye; presence of at least 7 branched anal-fin rays.

That said, detailed taxonomic work on the genus is long overdue meaning B. nunus and the majority of congeners are best considered nominal taxa for the time being since several other species might be involved.

Although we've assigned images of Brachygobius spp. to profiles based on how well they match the key of Inger (1958) their identification can therefore only be thought of as tentative pending publication of a forthcoming review.

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 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.