Large numbers of fish were found dead in a stretch of the Cauvery river in Tiruchirappalli, raising alarm among residents and river users.
Visuals from the spot show fish lying in heaps along the river edge, with the incident described as sudden and unusual.
The incident has drawn attention after a video clip of the scene began circulating, prompting questions over what may have led to the deaths.
No official cause or detailed assessment was cited in the source report, and further clarity is awaited.
