Wildlife experts in Bangladesh say they have moved nearly 500 rare turtles from a pond adjoining a shrine in the south-eastern city of Chittagong.
The turtles may have been poisoned by pesticides
Officials were forced to evacuate the black soft-shelled turtles after their water was poisoned.
Thousands of fish have already been killed in the poisoning.
The turtles are believed to be extinct in most places except Bangladesh, and are especially revered by the country's Hindu minority.
The BBC's Waliur Rahman in Dhaka says that the poisoning is the second incident in six months.
Last year, hundreds of catfish were poisoned in a pond outside a shrine in the northern city of Sylhet.
Our correspondent says that the arduous job of shifting hundreds of black soft-shelled turtles began on Wednesday morning, when custodians of the 1200-year old-shrine found that the pond was poisoned.
All the fish in the pond died, and soon the rare turtles also started to look ill.
A wildlife expert in Chittagong, Tapan Kumar Dey, said that all were then netted from the pond and transferred to another body of water.
He said initial investigations showed that pesticides were poured in the pond.
The turtles are one of the main attractions of the shrine, which is visited each year by thousands of people of all faiths.
Conservationists say that black soft-shelled turtles are only found in Bangladesh and parts of the Indian state of Assam. Otherwise they are extinct in the world.
Legend says the animals represent the souls of long-ago sinners, transformed into reptiles.
No one has claimed responsibility for the poisoning, which some believe was a deliberate attempt to kill the turtles.
The custodian of the shrine, Habibur Rahman, said it could have been carried out by hard-line Islamists opposed to their religion being associated with the creatures.
An investigation into the incident has been ordered by the authorities.