Coastal India & Sri Lanka

Almost every cichlid on Earth lives in Africa, Madagascar, or the Americas — but a tiny handful break the pattern, and they live here, in the fresh and brackish coastal waters of peninsular India and Sri Lanka. The chromides of the genera Etroplus and Pseudetroplus are the only cichlids native to Asia, and they are not a marginal curiosity: molecular phylogenies place their subfamily, the Etroplinae, as a deep early branch of the whole cichlid family, the surviving sister of Madagascar's Paretroplus and a living relic of the time when India and Madagascar were joined as one Gondwanan landmass. There is no single 'lake' to describe here. Instead there is a coastline — the estuaries, tidal lagoons, palm-fringed backwaters, and lower river reaches that rim southwestern India and Sri Lanka — where a salt-tolerant fish lineage has held on for tens of millions of years, and where one of its members, the karimeen, is prized enough to be the state fish of Kerala.

Setting & origin

This is a region rather than a single water body: the low-lying coastal belt of peninsular India — concentrated along the southwestern (Malabar) coast through Goa, Karnataka and Kerala, and reaching up the western seaboard toward Gujarat and around to Odisha's Chilika lagoon on the east coast — together with the lowland coasts of Sri Lanka. The shared waters are the in-between places: river mouths and estuaries, shallow brackish lagoons, the labyrinth of interconnected lakes and canals known as the Kerala backwaters (a network running some 560 miles / 559 mi along the Malabar coast, fed by more than 40 rivers draining off the Western Ghats into the Arabian Sea), and the lower, tidally influenced reaches of the coastal rivers themselves. The two countries that share this fauna are India and Sri Lanka.

What makes the place matter out of all proportion to its size is biogeographic. The cichlids living here — Etroplus and Pseudetroplus — are the only members of the family native to Asia, and they are no late arrivals. In the molecular phylogeny of Sparks & Smith (2004, 2008), the subfamily Etroplinae unites the South Asian chromides (Etroplus / Pseudetroplus) with Madagascar's Paretroplus, and that combined lineage falls out as the sister group to essentially all other cichlids — the African, Neotropical and remaining Malagasy radiations. The reading is straightforwardly Gondwanan: an ancestral cichlid stock was carried on the Indo-Madagascar block, and when India rifted away from Madagascar in the Late Cretaceous, roughly 88 million years ago, the lineage was split in two. Madagascar kept Paretroplus; the Indian raft kept the ancestors of Etroplus, which drifted north for tens of millions of years before India docked against Asia. The chromides of these coasts are, in other words, passengers from a vanished continent — which is why a few unassuming brackish-water fish carry so much weight in the story of how cichlids came to be.

Waters & chemistry

The defining chemical fact about these waters is that the salinity moves. These are estuarine and lagoonal systems where freshwater river discharge meets the sea, so salt content swings with the tide, the season and the place. Chilika Lake in Odisha — the largest brackish lagoon on the Indian coast and a Ramsar wetland — is a useful gauge: published surveys record salinity ranging from around 2 practical salinity units in the monsoon-flushed interior up to roughly 29 near the sea mouth, water temperatures around the upper 80s °F (about 81–88 °F), and pH that stays alkaline through most of the lagoon, commonly 8.0–8.8 and reaching higher near the mouth. The Kerala backwaters behave similarly: a dynamic freshwater-to-brackish gradient that shifts seaward in the dry months and freshens during the southwest monsoon, with barrages and bunds built for rice farming now interrupting the natural mixing in places. In Sri Lankan coastal lagoons, the green chromide has been recorded across an enormous salinity span — from nearly fresh (about 0.02) to roughly 28 — with pH measured anywhere from about 5.0 to 9.6 (Seriously Fish, after the Sri Lankan field literature).

The honest caveat is that there is no clean, lake-style limnological profile to quote for a coastal region this varied; the numbers above are representative of particular sites and seasons, not a single uniform body of water. What the chromides share is the adaptation that lets them ignore the swings: they are euryhaline, physiologically able to hold their internal salt balance across fresh, brackish and even full-strength seawater. Etroplus suratensis has been kept and studied across salinities from 0 to 35 parts per thousand; the orange chromide Pseudetroplus maculatus showed no significant difference in growth or survival reared at 0, 15 and 35 ppt and will breed across that range. Reported temperature tolerances sit in the tropical band — FishBase and aquarium-literature figures for E. suratensis cluster around 68–86 °F (about 68–86 °F) — and the green chromide can even gulp atmospheric air to cope with the low-oxygen conditions that brackish backwaters periodically fall into.

Habitats

The habitat that defines this fauna is the brackish margin — the zone where a river loses itself in the sea. Etroplus suratensis, the largest of the chromides, lives mainly in estuaries, coastal lagoons and the lower reaches of rivers, ranging into adjacent freshwater lakes and reservoirs; it favors quieter, vegetated, often turbid water over mud and sand, where it grazes a broad omnivorous diet of plant matter, detritus, small invertebrates and algae. The smaller orange chromide, Pseudetroplus maculatus, overlaps with it through the estuaries and backwaters but pushes further into pure freshwater and into more sheltered, structure-rich water, spawning on cleaned rocks and submerged wood.

Upstream, past the reach of the tide, the picture changes. About 30 miles (31 mi) inland of the river mouths the brackish-tolerant species drop out, and in the clear, fast, forested headwater rivers of the Western Ghats a third species takes over: Etroplus canarensis, the Canara pearlspot, a strict freshwater fish confined to the Kumaradhara–Netravati river system in southern Karnataka. Its world is the opposite of the others' — rocky, flowing, freshwater hill streams rather than still brackish lagoons — and that narrow, specialized habitat is exactly why it is so vulnerable. Across all three, the binding theme is that these are lowland-to-foothill coastal habitats tied to the Western Ghats drainage and the Sri Lankan wet zone, shaped far more by the rhythm of the monsoon and the push-and-pull of the tide than by depth or stratification.

The cichlids

Three native species carry the entire Asian cichlid story. The green chromide, Etroplus suratensis — known in Kerala as karimeen and across India as the pearlspot — is the flagship: the largest Indian cichlid, reaching around 16 inches (about 15.5 in) total length, a deep-bodied, greenish, pearl-spotted fish of the estuaries and backwaters. It is a serious food fish, not merely an ornamental one; in Kerala it is so culturally and commercially important that it was declared the official state fish in 2010, and demand for 'Kerala karimeen' runs several times ahead of supply, which has driven a growing brackish- and freshwater aquaculture effort. The orange chromide, Pseudetroplus maculatus (long known as Etroplus maculatus, and still often sold under that name), is the small, golden, black-spotted relative that aquarists worldwide know best — a hardy, characterful brackish cichlid and a genuine model organism for euryhaline physiology. The third, Etroplus canarensis, is the rarity: a small (roughly 4 inches / 4–4.5 in), strictly freshwater Western-Ghats endemic that was feared extinct for over a century after its 1877 description until it was rediscovered in 1992.

Two biological traits unite them and explain their success. The first is euryhalinity — the ability to live across the full sweep of salinities that a tidal estuary throws at them, which is precisely what let an ancient lineage persist on a shifting, salt-streaked coastline. The second is the hallmark cichlid behavior: devoted biparental care. Both chromides form pairs, clean a spawning surface, lay a clutch of a few hundred eggs, fan and guard them, and then shepherd the fry — and remarkably, like Madagascar's Paretroplus and unlike most other cichlids, the larvae of Etroplus feed on a mucous secretion from the parents' flanks, a trait shared with their Malagasy cousins that quietly underlines the Gondwanan family tie. All three are kept in the aquarium hobby, the orange chromide most of all.

People & pressures

For people, the green chromide is the heart of the matter. Karimeen is a high-value table fish woven into the cuisine and inland fisheries of Kerala, and across peninsular India and Sri Lanka the chromides support estuarine and lagoon fisheries that feed coastal communities. That value cuts both ways. In Vembanad Lake — the largest of the Kerala backwaters and itself a Ramsar site — fishers and researchers report a steep decline in the state fish, driven by mangrove clearance, backwater tourism, saltwater-exclusion barrages built for paddy cultivation that block the brackish mixing the fish depends on, pollution, and competition from introduced tilapia. The response has been to lean harder into aquaculture: pearlspot is now a favored candidate for pond culture precisely because it tolerates both fresh and brackish water, and hatchery seed production is being scaled up to close the gap between demand and a shrinking wild catch.

The most acute conservation case is Etroplus canarensis. Where E. suratensis and P. maculatus are widespread and currently assessed by the IUCN as Least Concern, the Canara pearlspot is listed as Endangered — its entire global range is two rivers in one district of Karnataka, an extent of occurrence under 5,0 mi² and an area of occupancy under 311 mi². Sand mining, agricultural pollution, dam and hydropower pressure on the Kumaradhara–Netravati system, and over-collection for the aquarium trade all bear down on a fish that has nowhere else to go; captive breeding in Southeast Asia has helped ease wild-collection pressure but cannot protect the rivers themselves. The broader pressures on the region — coastal development, mangrove and wetland loss, pollution, sand extraction and the reworking of estuarine hydrology — fall on the same brackish margins that made an Asian cichlid fauna possible in the first place.

Sources

Last reviewed 2026-06-06.

How to cite

Aquarist Atlas (2026). Coastal India & Sri Lanka. Aquarist Atlas. https://www.aquaristatlas.com/water/india-sri-lanka/

Setting & origin

Waters & chemistry

Habitats

The cichlids

People & pressures

Sources

Where every species has been recorded

Sources