Fish epidemic outbreak in California California is set to "humanely euthanize" 350,000 rainbow trout due to disease rapidly spreading through the state's population (https://fxn.ws/39ZeoXc). Californian rainbow trout populations at two government hatcheries are currently seeing a spike in bacterial infections that threaten the species' long-term health. Approximately 350000 trout are thought to be affected. Lactococcus petauri is a natural bacterium that can cause bulging eyes, erratic movement and high mortality in fish populations. The bacteria very rarely jumps from fish to humans. The state Department of Fish and Wildlife announced it would be using "two different types of fish vaccines (immersion and injection) developed by scientists at the University of California, Davis, at the affected hatcheries."