An assortment of undescribed Oreichthys spp. from India, Myanmar and Thailand are currently traded as O. cosuatis. It can be distinguished from other described members of the genus by lacking a black blotch on the caudal peduncle, plus the following combination of characters: 2-3 perforated scales in lateral line; ½6½ between pelvic-fin origin and dorsal midline; presence of dark stripe in centre of anal-fin, forming a triangular blotch in adult individuals; dorsal-fin with whitish tip and broad, black, subdistal margin in the upper portion of the fin; 11-13 rows…

This species is uncommon in the aquarium trade which is a little surprising given its huge natural range. Different populations can vary in colour pattern to an extent though all share the defining aspects given by Hamilton, comprising a diffuse yellow-golden marking on the operculum plus a dark spot on the caudal peduncle. The latter is usually surrounded by a variably-sized golden-yellow margin, and the dorsal-fin often contains irregular dark spots and streaks, these sometimes forming a longitudinal band.

In P. phutonio the flank markings comprise two black, vertically-orientated blotches, one posterior to the operculum and the other on the caudal peduncle, and within the P. conchonius group this patterning is shared with P. bandula, P. cumingii, P. didi, P. meingangbii, P. padamya, and P. tiantian.

It can be told apart from these by the following combination of characters: smaller adult size of 25 – 30 mm vs. at least 35 – 40 mm; minute maxillary barbels; incomplete lateral line with ab…

In the Barak River drainage, which flows through the north-east Indian states of Nagaland and Assam before bifurcating at the Bangladesh border, symaptric species include Barilius bakeri, B. barna, B. bendelisis, B. dogarsinghi, Laubuca laubuca, Esomus danricus, Devario aequipinnatus, D. annandalei, D. devario, Rasbora daniconius, R. rasbora,…

X. cancila is often seen referred to as ‘freshwater garfish’, and although it does superficially resemble the true gars of the family Lepisosteidae, it’s actually a member of the Belonidae, or needlefishes, the majority of which are marine or estuarine in existence.

There are currently just two species in the genus although the probable existence of a third member has been noted by Roberts (1989) among oth…

This species is also referred to as ‘Asian knifefish’ or ‘ghost knifefish’ in the aquarium trade in the aquarium trade but arguably has no place in the ornamental hobby given its adult size and specialised requirements.

It is sometimes confused with the African species Xenomystus nigri but is easily told apart by its larger adult size and presence (vs. absence) of a dorsal fin.

Traded under various names including ‘mottled’, ‘eyepot’, ‘sand’ and ‘striped’ loach. It’s perhaps one of the better choices for those new to keeping nemacheilids being relatively hardy, peaceful and exhibiting some quirky behavioural traits. The characteristic ocellus, a dark marking at the top of the caudal peduncle that resembles an eye, is thought to have some function in predator distraction and is normally more intense in younger specimens.

Butis spp. are largely nocturnal ambush predators with cryptic patterning to help them blend in with their surroundings. They can also lighten and darken their body colouration to an extent, have a habit of aligning themselves with solid surfaces whether horizontal, vertical, or inverted, and often swim in an upside-down position.

The genus is usually included in the family Eleotridae of which members are often referred to…

This species’ name has been widely misapplied in the aquarium trade and hobbyist literature, most often in reference to the Southeast Asian species C. ornata, but unlike its relative is in fact very rarely exported for ornamental purposes although its is fished and cultured for food in India.

It can be told apart from C. ornata by possessing fe…

Following Grant (2007) this species is included in the B. dario complex of closely-related species within the genus alongside B. striata. They're characterised by body patterning consisting of a base yellow to golden colour with 7-9 blue, green, grey or black body bars usually with thinner, lighter bars between. In some individuals the…