Clearwater plans to release 10,000 eastern mosquitofish into four city lakes Friday, Sept. 25, as dengue fever cases across the Tampa Bay region approach 200.

The fish eat mosquito larvae before they hatch into biting adults. The city's move comes as Hillsborough and Pasco counties declared local states of emergency over the virus and one Hillsborough County resident has died.

Cases climb across Tampa Bay counties

The Florida Department of Health has confirmed 190 locally acquired dengue cases statewide in 2026, according to figures first reported by WTSP. Hillsborough County accounts for 170 of those cases. Pinellas County has seven, its first locally acquired dengue infections in 15 years. Pasco County has two.

Thirty-eight new cases were confirmed in the week of Sept. 13-19 alone. August was the worst month, with 126 cases reported statewide.

The first confirmed dengue death in Florida this year was a Hillsborough County resident who died Sept. 4, according to WTSP. The Florida Department of Health confirmed the death Sept. 19.

Jill Roberts, a professor of molecular epidemiology at the University of South Florida, told WTSP that most dengue infections are mild but that death is more likely in patients who have been infected before.

"Stay indoors, and in places that have screens on the windows and doors," Roberts said. "Keep the doors closed so mosquitoes don't come into your house."

Counties declare emergencies, expand spraying

Hillsborough County Administrator Bonnie Wise signed an executive order declaring a local emergency that took effect Thursday, Sept. 24, and lasts seven days, according to Spectrum Bay News 9. The declaration gives county administrators authority to act quickly on public health measures and opens a path for federal reimbursement. The Pasco Board of County Commissioners issued its own emergency declaration Wednesday, Sept. 23, granting the county administrator authority to waive normal procedures.

Pasco County Commission Vice Chair Seth Weightman said the fight will require cooperation across county lines, according to Fox 13.

Pinellas County Mosquito Control warned Sept. 1 that "dengue does not stop at county lines" and expanded truck fogging and ground inspections in St. Petersburg, Palm Harbor, Clearwater, Safety Harbor and Oldsmar.

How fish and residents can fight back

The eastern mosquitofish, a Florida native, feeds on mosquito larvae and pupae in standing water. Pinellas County Mosquito Control breeds the fish and stocks local waterways as a biological control method.

The Centers for Disease Control and Prevention and the Florida Department of Health recommend wearing long sleeves and pants outdoors, using insect repellent and dumping standing water around homes. Dengue symptoms include fever, aches, nausea and rash. They typically appear within two weeks of a bite. There is no specific medicine for dengue. The CDC recommends rest, fluids and acetaminophen for pain.

Clearwater has not identified which four lakes will receive the fish or said whether additional releases are planned.