PETA scolded the Park Service Friday over the treatment of fish on Washington's National Mall, after two weeks of scorching temperatures led to a massive fish kill there.

The People for the Ethical Treatment of Animals sent a letter to the head of the National Park Service, Jonathan Jarvis, urging the agency not to restock the Constitution Gardens pond or risk more inhumane cruelty to the "intelligent" aquatic individuals under its care.

"Fish are intelligent, sensitive individuals, and the barren, ornamental pond on Constitution Gardens deprives them of the complex environment they need to thrive," said PETA President Ingrid Newkirk. "PETA is urging the National Park Service, which admits that this pond has been a death trap for fish since it was built in 1976, to stop restocking it."

The group said the Park Service knew of the risks in 2013 when thousands of fish died in the same pond due to prolonged high temperatures. The pond is centrally located among the Washington Monument, World War II Memorial and Vietnam Veterans Memorial. This month's fish kill has sent a foul smell into the air at the height of the summer tourist season and has seen park officials scrambling to remove the hundreds of rotting fish cadavers floating on the pond's surface.

"There are already so many intriguing attractions that enhance visitors' experiences on the National Mall, so I hope you will not simply acquire new live animals, as after the 2013 incident," Newkirk wrote.

The shallow depth "and poor construction" mean the pond is not a balanced ecological environment, PETA said Friday. The Park Service earlier this week admitted as much in an interview with the Washington Post, saying it is preparing to upgrade the pond to make it a more conducive habitat.

The high temperatures, which rose above 90 degrees for much of the last month, heated the pond's water, depriving it of oxygen and suffocating the fish. The heat also caused algae blooms that further removed oxygen from the pond.

PETA reiterated its motto, "animals are not ours to abuse in any way," to the Park Service.

Fish "have distinct personalities, develop relationships, talk to each other, show affection through gentle rubs, and grieve when their companions die," PETA said.

PETA also quoted Sylvia Earle, referring to her as one of the world's leading marine biologists, who said, "I wouldn't deliberately eat a grouper any more than I'd eat a cocker spaniel. They're so good-natured, so curious. You know, fish are sensitive, they have personalities, they hurt when they're wounded."