The officials said pollution and lack of oxygen in the lake was the reason for the death of fish.
After the death of thousands of migratory birds in Rajasthan's Sambhar lake, several crows and fishes have now been found dead in the Ana Sagar Lake in Ajmer in the last three days.
The forest department buried around 30 crows in the Ghooghra nursery in Ajmer and were awaiting the viscera report from Bhopal to find out the cause of the death.
The officials confirmed that crows found in and around the Ana Sagar lake appeared feeble and inactive and hence it is feared that the death toll might increase.
Initially on Friday, 19 crows were found dead and then on Sunday, 11 more were found dead. Also, over 100 fish were found dead in the lake on Saturday.
The officials said pollution and lack of oxygen in the lake was the reason for the death of fish.
During winters the Ana Sagar lake attracts thousands of migratory birds.
A senior official of the animal husbandry department said that reports of crows found dead were received on Saturday, "Our team reached there. The forest officials, police and other teams had already reached the site."
The locals have accused the forest department and animal husbandry department of initially hiding the reports about the death of crows.
The post-mortem on the dead crows was conducted at the veterinarian hospital and bodies were then handed to the forest department, who then sent the viscera and post-mortem report to Bhopal for further examination.
The officials said that there were chances of crows dying due to some poisonous food. But, the question was who could have spread the food around the lake and this needed to be investigated, they said.