RICHMOND, Va. (WFXR) — You reel in the bass and notice that it does not look like any largemouth you have caught before. It is covered with large black blotches that look like someone may have tossed ink on the fish.

What is it?

Scientists and fisheries managers say it is something called Blotchy Bass Syndrome. For a long time, the condition was a mystery, but researchers now know it is caused by a virus, specifically an adomavirus, and that the virus has been found in fish across much of the country.

Fisheries experts say the blotches are a stress response that causes patches of black pigmentation. It appears to have no severe effects on the fish it infects, though more research is being done. The virus does not affect humans. It appears to be confined to fish, primarily to black bass species like largemouth bass, smallmouth bass, and spotted bass.

Because viruses can mutate, fisheries managers around the United States and Canada, including Virginia, are tracking Blotchy Bass Syndrome. The Virginia Department of Wildlife Resources (DWR) is asking for your help. If you catch a bass with dark blotches, you are asked to report it. Various state and federal agencies have partnered with Angler’s Atlas, and reports can be made through Angler’s Atlas MyCatch app.

Smallmouth bass with ink blot pigmentation changes caused by adomavirus (Photo: USGS)

While many people do not keep and eat bass, scientists say that for those who do, fish with Blotchy Bass Syndrome can be eaten if they are cleaned and cooked properly.