It might seem like a wildlife mystery: dead fish ending up in the Concho River. But there’s nothing fishy about it. In fact, there is a real, scientific explanation behind what’s been going on.

On the banks of the Concho River near Miles, nature is alive and thriving.

But just off-shore, other native species haven’t been so lucky. Carp, Buffalo, Shad and friends are either stuck on barriers or mercilessly float to the river’s rhythm. And, as it oftentimes goes, it’s survival of the fittest in these waters – and these gill-breathers stand no chance.

“Golden alga is basically a microscopic, single-celled alga species. It occurs naturally in our waters. It’s in every water throughout West Texas,” Lynn Wright, with the Texas Parks and Wildlife Department’s (TPWD) inland fisheries, said.

Prymnesium parvum, its classroom name; golden alga, its street name. in low-levels, the alga does no harm to life around it, but under the right conditions, this microorganism grows out of control – known as a “golden alga bloom.” Soon, toxins are released into the water. Those toxins eat away at fish scales, until their gills are so badly damaged they don’t work anymore.

And unlike other species of alga, golden alga is the one researchers know the least about.

“Golden alga is different because it’s something, even though we’ve spent a lot of time studying it, we don’t know all the factors that cause it to bloom. So, it’s difficult to predict where it’s going to happen,” Wright said.

So, what do they know? Well, golden alga prefers salty water. The first fish kill took place on the Pecos River back in 1985. Since then, other blooms have developed – but this latest one is incredibly unique.

“This is as close to San Angelo as we’ve seen one,” Wright said.

Never before has a bloom hit so close to home. It’s also rare for a bloom like this one to happen so late in the season. Golden alga grows best between January and March, when the competition between other species is low.

And while the toxins don’t pose any harm to humans, livestock or other mammals, it’s a toxic start to the fishing season for West Texas’ avid fishers.

“When you have a bloom, you could lose 70 to 80 percent of your fish, maybe even more. But you will have some survivors that will repopulate the area. It may take several years, but part of the river will get back to normal eventually,” Wright said.

Wright said there is no telling when the alga will die. It could take months for it to clear out.

As of now, the TPWD will continue to monitor this stretch of river and supply updates when necessary.