Plaquemines Parish officials have also asked the Louisiana Department of Wildlife and Fisheries why so many fish were killed in the area.
“We can't continue to see these fish kills. We need some additional tests to find out why these fish are dying in large numbers. If it is low oxygen, we need to identify the cause,” said Mr Nungesser.
BP's Deepwater Horizon oil rig exploded off the coast of southern Louisiana in April, killing 11 people and leaking an estimated 4.9m barrels of oil into the Gulf of Mexico.
The Plaquemines Parish area was heavily affected by the spill.
Ed Overton, an environmental scientist at Louisiana State University, said warm temperatures and a lack of wind can rob water of oxygen and in turn cause fish kills in late August and early September.
But Mr Overton questioned whether the BP spill had played a role in the mass fish deaths.
“It is improbable, not impossible, that this is the result of oil toxicity,” Mr Overton said.
“The oil that's in the shoreline right now doesn't have a lot of the volatile components.”
But Mr Overton conceded that bacteria in these types of waterways can use up oxygen when degrading oil, which can then affect fish.