Karamana basin

Opsarius bakeri is a fast-swimming cyprinid endemic to the Western Ghats of southwestern India, with records from many rivers in Kerala and Karnataka. It is traded as 'royal danio', 'blue-spotted hill trout' and 'blue-dotted mirror fish', and has a single row of bluish-green spots that get smaller with age. Its well-oxygenated, fast-flowing rivers are being polluted and degraded by exotic species and sand mining.

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 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.