The city told ABC7 News that 500-1,000 fish have died in Central Park's Lake Elizabeth.
VIDEO: How Alameda County Fair officials are protecting livestock during heat wave
How Alameda County Fair officials are protecting livestock during heat wave
Crews began cleaning up the fish shortly after they were discovered Wednesday.
Fremont officials say the recent heat is lowering oxygen levels in the water as well as the overall water level.
The city is trying to raise the water level to help protect the surviving fish.