La Quinta -- Two employees of a La Quinta pet store allegedly killed hundreds of fish at the business by pouring bleach into the water, authorities said Monday.

Sora Matsunaga, 18, and a 17-year-old suspect -- whose name was withheld due to age -- allegedly dumped bleach into the main water circulation system killing about 500 fish in 36 tanks, according to the Riverside County Sheriff's Department.

The property loss was placed at $15,000.

The incident happened shortly after the PetsMart opened on Oct. 12, said sheriff's Lt. Raymond Gregory.

The suspects were arrested on suspicion of vandalism, conspiracy and animal cruelty, authorities said.

An investigation revealed "some employees had been recently dismissed from the location and some of the remaining employees were unhappy," Gregory said.

Investigators focused on Matsunaga and the 17-year-old, who confessed Friday to conspiring to kill the fish, Gregory said.

"My understanding is ... something about the dismissals of those other employees caused (the suspects) to be angry," the lieutenant said. "They committed these acts to distress the manager."

The suspects were released from custody shortly after their arrests.

According to Gregory, as of last week, the suspects were still employed at PetsMart, but store supervisors were expected to take "appropriate disciplinary action."