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Spot a blotchy bass, send a photo to Texas Parks and Wildlife

black bass with blotchy bass syndrome

Anglers catching a black bass with black spots or blotches on it are asked to email a photo of the fish and the location where it was caught to Texas Parks and Wildlife Department fishery biologist Dr. Cynthia Fox Holt at to help identify the distribution of blotchy bass syndrome. Photo courtesy of TPWD

If you catch a blotchy bass, let the Texas Parks and Wildlife Department know. The department is asking anglers who snag a black bass species with dark blotches on its scales to send it a photo of the fish and the location where it was caught. Its part of a multi-state effort to map out and investigate blotchy bass syndrome, also known as hyperpigmentation/melanosis.

Scientists have documented the condition in 18 states, including Texas, according to Dr. Cynthia Fox Holt, Ph.D., a TPWD fishery biologist.

“So far, it doesn’t go farther west than Texas,” she added. 

The condition doesn’t appear to harm the fish, and it’s not  transmissible to humans or domestic animals.

“Historically, we’ve never known the cause of blotchy bass syndrome,” Holt said. 

It was first presented in a scientific platform in 1982, though anglers had previously reported it. Scientists have speculated that it is caused by stress from fishing or environmental issues or from sun exposure. It wasn’t until an aquarium asked researchers at the U.S. Geological Survey Eastern Ecological Science Center in West Virginia to examine some of its blotchy fish that scientists identified a probable culprit.

“They took some swabs from the fish, and (the condition) was associated with a family of viruses,” Holt said.

Biologists and anglers had also noted the condition in healthy wild populations of black bass as well as trout, catfish, and char. 

After identifying the cause as a virus, questions remained, including the syndrome’s range and distribution, its effect on wild fish populations, and how it is transmitted.

“We see it in small, private pounds that have never been touched by other bodies of water,” Holt said.

The Eastern Ecological Science Center team reached out to state fish and wildlife agencies to collect basic information on fish exhibiting the syndrome. 

Holt is the state of Texas’ point of contact. She’s asking anglers in the state who catch a black bass exhibiting the syndrome to take a photo of the fish and email that along with the catch’s location to And, if anglers are willing to share them, the GPS coordinates would be helpful.

Researchers at least need the county in which the fish was caught and the type of water body: lake, river, pond, etc. Initially, scientists will group the identified blotchy bass syndrome fish by watersheds. 

While the condition is found in other species of fish, this study is focused on black bass species, including largemouth, smallmouth, spotted, and Guadalupe. 

Since Holt posted the request on social media, more than 200 anglers have submitted photos of bass with the condition.

“The support from (Texas) anglers has been phenomenal,” she said. “Really makes me proud to work for a state agency whose anglers are so interested in the health and conservation of resources.”

The condition, while visually unpleasant, doesn’t appear to affect the general health of the fish, which are safe to eat if handled and cooked properly, as with any other fish. And anglers can release the blotchy fish back into the water, Holt added.

Fishery biologists will swab and collect samples from any blotchy bass they catch during their normal surveys and send the samples to the Eastern Ecological Science Center to determine if the virus found in the Texas fish is the same as the one identified in West Virginia and other states.

“Then, they’ll try to determine a cause,” Holt said. “Plus, this is not specific to Texas, so any angler who lands a fish with blotchy bass syndrome, we’d love to get a photo and location as well. It all goes to help figure this out.”