A pending lawsuit intended to protect an endangered fish found near the site of the future Toyota-Mazda manufacturing facility picked up a new plaintiff Tuesday.

Tennessee Riverkeeper, a Decatur-based conservation group, announced it had joined the Center for Biological Diversity in filing a formal notice of intent to sue Mazda Toyota Manufacturing U.S.A. The CBD, which has an office in St. Petersburg, Florida, filed its own notice of intent to sue July 25.

The groups are concerned about the well-being of the endangered spring pygmy sunfish, which measures about 1 inch in length. The fish inhabits creeks, streams and wetlands near the site of the $1.6 billion manufacturing facility under construction in Huntsville-annexed Limestone County.

“We need to take every step we can to ensure that we protect the abundance of aquatic biodiversity God blessed us with, including the spring pygmy sunfish,” said David Whiteside, executive director of the Tennessee Riverkeeper, in a statement. “We don’t have to choose between jobs or clean water. We can have both by ensuring existing laws are enforced. These are values shared by Republicans, Democrats, and Independents.”

Mazda-Toyota spokeswoman Kim Ogle on Tuesday said the companies remain committed to preserving and sustaining the habitat of the spring pygmy sunfish.

“We will continue engaging with the Center for Biological Diversity, third party experts and other key stakeholders in developing and executing on a conservation strategy that works to preserve the spring pygmy sunfish and its habitat,” she said.

Both the CBD and Tennessee Riverkeeper believe the joint automotive project, which is set to hire about 4,000 workers, poses a pollution threat to the habitat of the fish. In 2013, the U.S. Fish and Wildlife Service moved to protect the fish under the Endangered Species Act.

In a joint statement, the conservation groups point out FWS officials explained the changing land use “from rural to urban/industrial within the Beaverdam Spring/Creek area will be detrimental to the spring pygmy sunfish.”

Citing concern over how the fish was being protected by construction activities, officials with Mazda-Toyota and the city of Huntsville put a temporary halt on the project in late July. Work resumed about a week later.

The automakers and Huntsville officials hosted a tour for CBD to demonstrate measures being taken to protect the fish, including site grading, construction best-management practices and related activities. Those preventative measures were not deemed satisfactory by CBD or the group’s attorney, Elise Bennett, who is also representing Tennessee Riverkeeper.

“Both Toyota and Mazda are responsible for making sure they don’t wipe one of Alabama’s rarest fishes off the face of the earth,” Bennett said. “If these companies want to be good neighbors, they’ll put comprehensive protections in place before it’s too late for the sunfish.”