The Town of Huntington says about 10,000 bunker fish have washed up in the Mill Dam in Centerport.
The town says about 2,000 adult fish and 8,000 young fish were caught in low tide and died from a lack of oxygen.
Huntington Town Spokesman A.J. Carter says high tide should displace the fish into the nearby harbor, where they will sink.
If the fish are not displaced by the high tide, the town says it will remove them with nets and machinery.
Carter says the fish kill is not an issue of water quality or pollution. The town hopes to have the dead fish problem resolved in the next three days.