In a scramble to clean up a large fish die-off last month, park rangers buried fish in a mass grave to mask the smell, a city administrator went “incognito” to dodge reporters, and employees were rushed in to work overtime over a holiday weekend, new records show. The documents, obtained by this news organization through a public records request, paint a clearer picture of what happened in the days after a Bay Area heatwave killed about 1,000 fish in Fremont’s Lake Elizabeth. Rising water temperatures and leached oxygen from the manmade lake suffocated the fish between July 3 and July 6. It left an estimated five-ton fish mess on the city’s hands and forced staffers to scramble for a response. … Although “harmful algae blooms” were suspected, the city reaffirmed in an Aug. 2 news release that they were not a contributing factor.