Kelani basin

The Ceylonese combtail, Belontia signata, is a labyrinth fish endemic to the central and southern river systems of Sri Lanka. Also referred to as the 'Ceylon fighting fish', it differs from B. hasselti in its reddish body and the absence of mosaic patterning in the unpaired fins. At least three putative phenotypes have been recorded, one described as the questionably valid subspecies B. s. jonklaasi. It is not recommended for the average community aquarium.

The Ceylon snakehead, Channa orientalis, is a small snakehead without pelvic fins, endemic to the wet zone of southwestern Sri Lanka. Its name has been widely misapplied to Channa populations elsewhere in South and Southeast Asia, most of them now considered C. gachua. Probably endangered in the wild, it is a paternal mouthbrooder that forms lasting pair bonds, and captive breeding should be the priority when keeping it.

The ornate paradisefish, Malpulutta kretseri, is a labyrinth fish from the 'wet zone' of southwestern Sri Lanka. It has been recorded from the Gin, Kelani, Kalu, Nilwala and Bentota river basins. The only member of its genus, it is protected by law in Sri Lanka although it still appears in the aquarium trade from time to time. Three colour forms exist, differing in the amount of reddish, violet or bluish pigmentation in the fins.

The black ruby barb, Pethia nigrofasciata, is a small cyprinid endemic to the Kelani and Nilwala river basins in the 'wet zone' of Sri Lanka. Sometimes traded as 'purple-headed barb' or 'ruby barb', it has three dark, vertical flank markings, and in spawning males the head and front of the body turn reddish-purple. Farm-raised fish are fairly adaptable in water chemistry, while wild stock are likely to prefer slightly acidic to neutral conditions.

Pethia reval is a small cyprinid endemic to western Sri Lanka, known from the Kelani and Maha Oya river systems and the drainages between them. Considered a red-finned colour form of P. cumingii before its description, it is a smaller fish, to 33.6 mm SL, with red dorsal, anal and pelvic fins (pale yellow in the Kalu River population). The Mahaweli River population appears to have been introduced.

The orange chromide, Pseudetroplus maculatus, is a euryhaline cichlid native to peninsular India and Sri Lanka. It mostly inhabits brackish estuaries, coastal lagoons and the lower reaches of rivers, and can be kept in fresh or brackish water so long as acidic conditions are avoided. Wild examples are rarely seen in the hobby, where selectively bred strains traded as 'red' or 'yellow' chromide are widely available.

The spiketail paradisefish, Pseudosphromenus cupanus, is a small labyrinth fish restricted to southern India and Sri Lanka. It lives in sluggish and still waters such as rice paddies, swamps and weedy ponds. It lacks the two dark lateral stripes of its only congener, P. dayi. A secretive bubble nester, it is peaceful but too small and timid for most community aquaria.

The swamp barb, Puntius chola, is a cyprinid from much of Pakistan, India, Nepal, Bhutan, Bangladesh, Sri Lanka, Myanmar and western Thailand. Sometimes called the 'chola' or 'green' barb, it has a single pair of barbels and dark blotches behind the operculum and near the caudal-fin base. It apparently prefers stiller waters over mud or silt, and makes an ideal addition to a peaceful community of riverine fishes.

The cherry barb, Puntius titteya, is a small cyprinid endemic to the Kelani and Nilwala river basins in the southwestern 'wet zone' of Sri Lanka. Among the most ubiquitous small cyprinids in the hobby and an unreserved choice for beginners, it is sold mostly as commercially farmed stock, including albino and 'super red' strains. Generally very peaceful, it is a schooling species and at least 6-10 should be kept.

The green chromide, Etroplus suratensis, is a euryhaline cichlid from peninsular India and Sri Lanka, growing to 350 mm SL. It mostly inhabits brackish estuaries, coastal lagoons and lower river reaches. Not especially popular in the hobby, it is an important food fish, and some populations have crashed through over-exploitation. In Sri Lanka's Negombo Lagoon Pseudetroplus maculatus has been seen acting as its cleaner while also eating its eggs and fry.

Kami's barb, Puntius kamalika, is a cyprinid endemic to Sri Lanka, widespread in the southwestern 'wet zone' between the Kelani and Gin basins. Common throughout its range, it has been collected from rivers, streams and marshland. Before its description it was referred to as P. amphibius, a putatively valid species probably restricted to western India, and it lacks prominent markings on the body and fins.