B. sabanus is very similar to B. doriae and these two are easily confused. However in B. doriae most of the first-dorsal-fin and two-thirds of the pectoral-fin are black while in B. sabanus the last one or two rays of the first dorsal-fin are colourless and less than half of the pectoral-fin is black.

In addition there are usually smaller dark ‘saddles’ betw…

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.

It can be diagnosed as follows: <30 lateral scales; two black body bands reaching ventral midline posterior to anal-fin; band above anal-fin also reaching ventral midline no black band on head, though the first band may touch the posterior margin of the eye; band above anal-fin not reaching ventral midline; 6 branched anal-fin rays; 7-8 predorsal scales. Brachygobius currently contains 9 described species but is likely to prove more diverse should a review be carried out. Alt…

Though this species appears on ornamental trade lists quite often the name appears to be routinely misapplied to other species, particularly B. doriae.

It can be diagnosed as follows: <30 lateral scales; two black body bands reaching ventral midline posterior to anal-fin; band above anal-fin als...

In live fish colour pattern is perhaps the most useful way to identify N. rubrocaudatus plus the closely-related N. marginatus and N. mortenthaleri. N. marginatus is immediately distinguished from the other two by the fact it lacks red pigmentation on the body in males, but N. mortenthaleri and N. rubrocaudatus are more easily-confused.

Males of N. rubrocaudatus can be told apart fro…

Described from ‘Igarapé Candiru-Mirim, Rio Capim, Pará, Brazil’, a relatively short river draining into the rio Pará near the city of Belem, eastern Brazil.

Records of similar-looking fish exist from Santarém, Pará state, in the central Amazon region, and the coastal city of Fortaleza, Ceará state, much further southeast. These may require confirmation.

Inhabits sluggish blackwater tributaries, small rivers and swampy areas, particularly in areas with dense growth of aquatic or overhanging riparian vegetation, submerged woody structures and leaf litter. The water is typically stained darkly with humic acids and other chemicals released by decaying organic material, the dissolved mineral content is generally negligible and pH can be as low as 4.0.

N. minimus occurs sympat…

This species is also known as ‘Marilyn’s pencilfish’. It’s rarely traded in numbers and more often seen as bycatch among shipments of other species, particularly Paracheirodon axelrodi.

It can be identified by the following combination of characters: three dark lateral stripes (sometimes referred to as primary, secondary, and tertiary); nocturnal oblique bars relatively narrow, with the anterior bar reaching, but not extending past, the anterior base of the dorsal-fi…

This species is poorly-known in the aquarium hobby but is sometimes exported as bycatch among shipments of other species, especially Nannostomus beckfordi to which it appears quite similar. The easiest way to tell the two apart is that N. grandis lacks pale white or bluish tips to the ventral fins.

It can be further distinguished from all congeners by the following combination of characters: body size up to 46.2 mm, the largest in the genus; bo…

This species is sometimes traded as ‘Espei’s’, ‘four-barred’ or ‘banded’ pencilfish and is sought after in the aquarium hobby, though normally quite expensive to buy.

It’s most-easily identified by its unique colour pattern of 5 dark, vertically-orientated bar-like markings on each flank, this in direct contrast to the horizontal stripes seen in other congeners…