Dozens of brim, catfish, and bass turned up dead Sunday morning in Marsh Creek in Brentwood Park.
Ernie Seneca of the Water Quality office said no dead fish were found Monday, but they could have been washed away.
Nothing unusual was found in the creek water tested today, sampling will continue.
It's a popular area with some people, who use the creek for fishing and play.
Workers from Raleigh Public Utilities also came out; they were checking for sewage leaks.
Marsh Creek runs into Crabtree Creek, which eventually spills into the Neuse River. State environmental investigators are expected to test the water and the fish for contamination.