Forest officials led by Conservator of Forest D Arun visited the 77-acre sanctuary after some villagers noticed the dead fish and informed them yesterday, officials said.
Arun said the water level in the tank had decreased drastically due to failure of rains which might have led to oxygen deficiency, causing the death of the fish.
He would take up the matter with the Public Works Department and seek release of some water into the tank through Lower Bhavani Project Canal.
