Need to document freshwater fish species in waterbodies, say conservationists

Conservationists urge documentation of freshwater fish species in Tamil Nadu's waterbodies, highlighting the importance of native species preservation.

Recently, a fish species called Rhinomugil corsula (locally known as Paravai Kendai) was sighted at the Maruthur irrigation tank near Melur in Madurai district. Once prevalent in Vaigai river, this species has almost died in the river system. This stray sighting of a species in a waterbody that has no direct link with the river shows that a study should be conducted to record species found in independent waterbodies, say researchers.

Madurai Nature Cultural Foundation (MNCF), which has been documenting freshwater fishes in waterbodies around the district, say that in 2024, they recorded 62 freshwater fish species in the Vaigai River basin, of which 11 were exotic species. Of these, four species listed in the International Union for Conservation of Nature Red List, including Kelaart’s Snakehead, Butter catfish and Sareng catfish, were also documented.

The study also revealed that exotic fish species outnumber native ones in the Vaigai river basin. Several native species such as Gangetic mystus, Whiskered Mystus, Common spiny loach, Reba carp, Barred spiny eel, Twospot barb, Kaveri rasboora, and Corsula have disappeared.

Tamizhl Dasan of MNCF says that the sighting of Paravai Kendai gains importance because in a study conducted by the Zoological Survey of India in 1986 by Dr. Indira, 19 freshwater fish species were listed in the Vaigai basin. However, in the 2024 study, these species, including Paravai Kendai, were not found in the river. “Thus, the sighting of the species in the irrigation tank gives us hope that more such species may be thriving in other waterbodies,” he adds.

Environmentalists also decry the introduction of exotic fish species such as Tilapia, Catla, and Rohu. Some of these species thrive well in polluted water when compared to native fishes, says researcher R. Kishore.

Steps should be taken by the Tamil Nadu government to implement special schemes to protect endangered freshwater fishes and their habitats and also, a study should be conducted to record and document the various species, say members of MNCF.