IDNR Report

Blotchy bass

If you have been bass fishing more than just occasionally, it’s likely you have caught a bass that had black botches on its body.

Scientists call it “Blotchy bass syndrome (BBS),” the occurrence of black ink-like spots (hyperpigmentation) on the skin, fins, and/or mouths of freshwater bass species.

Researchers once thought that melanosis was caused by sun exposure or stress related to fishing, temperature, or pollution; however, researchers recently discovered that a family of viruses was associated with the black spots in fish that were in poor body condition.

The Division of Fish & Wildlife is partnering with the United States Geological Survey (USGS) to collect samples from black bass species to test for BBS and needs your help. DNR encourages anglers to report observations of affected bass when you are fishing, so they and USGS can learn more about the effect of this family of viruses.  

How to participate:

• Download the MyCatch app from Angler’s Atlas.
• Register for the “Blotchy Bass Bonanza.”
• Take photos of all the bass you’ve caught (preferably on a measuring board) while fishing and upload them to the MyCatch app.

The Blotchy Bass Bonanza runs from March 1, 2023 —Feb. 29, 2024. The Indiana DNR is not associated with the MyCatch app or the Blotchy Bass Bonanza.