River or lake, India
Vembanad and the Kerala backwaters
Kerala's largest lake and the heart of its backwaters, home of the karimeen, the pearlspot.
Vembanad is the largest lake in Kerala, a long brackish water body that stretches from Kochi south towards Alappuzha and is fed by several rivers flowing down from the Western Ghats. With its canals, paddies and villages it forms the core of the Kerala backwaters. It was listed as a Ramsar wetland in 2002 and is the home water of the karimeen, or pearlspot, Kerala's state fish.
Karimeen and the clam fishery
The pearlspot is a green-and-pearl-spotted cichlid that lives in brackish backwaters, where pairs guard their young. Fried or cooked in banana leaf as karimeen pollichathu, it is a symbol of Kerala food, and Kerala declared it the state fish in 2010. The lake also holds mullets, snakeheads, climbing perch, catfish and giant river prawns, and supports a large black clam fishery.
The salt barrier
In 1975 the Thanneermukkom barrier was built across the lake to keep salt water out of the southern paddies of Kuttanad during the dry season. It helped rice farming but cut the movement of fish and prawns between the sea and the southern lake, and catches fell. Pollution, land reclamation, water hyacinth and invasive species such as the Amazon sailfin catfish add to the pressure. Farmers now raise pearlspot in ponds and cages to meet demand.
Still to be written: Green chromide, Channa striata, Anabas testudineus, Flathead grey mullet, Pterygoplichthys pardalis.