The mysterious death of fishes in the Sathanur dam in Tiruvannamalai district has left fishermen shocked. After noticing the dead fishes that were washed ashore on Friday, the fishermen alerted the authorities of the Tamil Nadu Fisheries Development Corporation (TNFDC), following which an official team rushed to the spot. Officers from Revenue, Tamil Nadu Pollution Control Board, PWD and TNFDC embarked on a boat to visit the spot where the fishes were found dead. Officials say the death could have been triggered by change of conditions as squally winds blew over the past few days resulting in deposit of excessive silt in the dam bed. "Change of conditions due to the movement of silt could have caused death. We are still ascertaining the cause of their death," an official, who visited the spot, told Express. The TNPCB officers have collected water samples which will be sent for laboratory tests. Around 1 to 1.50 ton of fishes are expected to have died in the last three days. Most of them belonged to jalebi, uluvai and pearl spot species. They were found lying dead in a highly decomposed state at Mani Odai, a far end of the dam bed. A few months ago, two fishermen were murdered by a group of poachers who resorted to illegal fishing in the dam bed around Mani Odai. Since then the officials have been patrolling the area with police protection.