HOUSTON, TX — An estimated 22,000 rainbow trout died when they gorged themselves on toxic "fire" ants that fell into a Texas river after mating in the sky, state officials said on Wednesday.

The sex-spent ants fell into the river, where the hungry trout gobbled them up.

The unusual fish kill took place last week on the Guadalupe River near the central Texas town of New Braunfels, the Texas Parks and Wildlife Department said.

Department biologist Andy Labay said the fish, which are not native to Texas, ate the ants without realizing they were toxic.

"Almost all the fish we cut open were gorged on fire ants," said department biologist Andy Labay. He said some trout had as many as 500 of the venomous ants in their stomachs.

The ants fly up into the air to mate after the first rains in May and June. The males die and fall back to earth, while the females land and start new colonies, Labay said.

In this case, the sex-spent ants fell into the river, where the hungry trout gobbled them up.

The dead trout were among 250,000 young trout that the Parks and Wildlife Department recently stocked in the Guadalupe for fishing.

Some trout had as many as 500 of the venomous ants in their stomachs.

Rainbow trout are not native to Texas because the state has very few of the cold-water streams the fish need to survive.

Fire ants are South American natives that began establishing themselves in the southern United States in the 1930s and are now a major nuisance across the region. They are known for inflicting painful and sometimes fatal stings on humans and animals.