California Confirms Largemouth Bass Virus Detection
The state's first confirmed case of the virus followed a die-off of about 220 fish at a private Nevada County lake.
Updated on Nov. 12, 2026 in Fishing
The California Department of Fish and Wildlife confirmed Largemouth Bass Virus in the state for the first time, after necropsies at its Fish Health Lab verified the infection in largemouth bass and bluegill at Lake of the Pines. A September die-off at the 232-acre private lake killed approximately 220 fish, mostly largemouth bass.
Why it matters
The virus can spread through contaminated equipment, infected baitfish and stocked fish, which affects anglers and the fisheries they rely on across California. Because there are no available treatments or vaccines, prevention depends on limiting the movement of potential carriers.
The virus was confirmed through necropsies of fish from a 232-acre private lake in Nevada County that lost about 220 fish in September. The infection source and the number of other affected waterbodies remain unknown.
The players
California Department of Fish and Wildlife (CDFW)
The state agency responsible for managing California's fish and wildlife resources, which confirmed the virus and is investigating whether it is present in other waterbodies.
The details
LMBV can be introduced through contaminated equipment, infected baitfish, stocked largemouth bass and other carrier species, and spotted bass, bluegill and crappie can carry and transmit the virus without showing symptoms. The virus does not pose any risk to humans or other warm-blooded animals, but surviving fish may eventually build resistance and populations can recover, though larger fish may be affected for years.
Timeline
• September: Fish die-off killed approximately 220 fish at Lake of the Pines.
• November 12, 2026: CDFW confirmed LMBV presence in California for the first time.
Roadmap
Largemouth Bass Virus was first documented in Florida in the 1990s and has since spread throughout the United States, and California's first confirmation extends that documented pattern into the West. The virus has no available treatments or vaccines, so its continued spread depends on how carriers and equipment are managed across the state's waterways.
Anglers who fish in California waterbodies should clean and dry equipment and avoid moving baitfish between lakes to reduce the chance of spreading the virus. Because spotted bass, bluegill and crappie can carry LMBV without symptoms, anglers may unknowingly transport it between waterbodies.
The takeaway
Because LMBV can spread through equipment and bait without visible signs in carrier fish, careful cleaning and avoiding the transport of live baitfish are the most practical steps anglers can take. Responsible habits protect both the fish that survive an outbreak and the long-term health of California's fisheries.
Further reading
Explore more on Fishing to see how anglers can protect California's waterways from aquatic disease.
