A massive fish kill in the Rocky River in Strongsville is still under investigation, with no new leads, an EPA spokesman said.

More than 28,000 fish in a 5-mile stretch of the East Branch between Strongsville's Bonnie Park and Berea were found dead April 23.

Authorities said they believe a chemical may have been dumped into the river, possibly near the area of Pearl Road and Progress Drive in Strongsville.

But Mike Settles, spokesman for the Ohio Environmental Protection Agency, said tests on the water came back inconclusive.

"There was nothing out of the ordinary in the water," Settles said.

A fisherman tipped off authorities to the dead fish on Sunday, April 22, sending officials from the EPA and Ohio Department of Natural Resources to Bonnie Park the next morning. 

Settles said the fact that the water tested clean on Monday indicates the fish were actually poisoned late the previous week.

"On the bright side, there's no lingering residue that will continue to harm the fish," he said.

It remains an open investigation, he said.

Anyone with information can call 334-683-2395. Callers can remain anonymous.