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DENVER, Colo. (CBS Local) — A passenger flying Southwest Airlines on Friday claims she was forced her to leave her pet fish behind at the Denver International Airport before her flight.

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Lanice Powless, a student at the University of Colorado, says she was ready to board her flight to San Diego with her pink betta fish “Cassie” when an airline employee told her pet wouldn’t be allowed to board.

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Powless said she had brought the fish along on other flights and had never encountered an issue. She had also checked the Transportation Security Administration website to see if she could fly home with the pet over the holiday break.

Indeed, TSA policy allows “live fish in water and a clear transparent container” on board to count as a carry-on bag “after inspection by the TSA office.”

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“I have traveled with it,” Powless told KGTV. “I had it in my container too.”

But it turns out Southwest has a stricter pet policy than TSA. The airline announced in August it was limiting passengers to one emotional support animal per person ― and only small dogs and cats in containers stowed under the customer’s seat are permitted.

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Powless said she handed Cassie over to another traveler going on a different airline. But the two got separated at the airport before they could exchange contact information.

“I don’t know where my fish is at,” Powless said. “I don’t know if they allowed her to take it.”

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Powless says she was not offered the option to re-book the flight. But Southwest said it “offered to re-book the Customer for a later flight to allow them to make arrangements for their pet but the Customer refused that option. The Customer eventually traveled on their originally scheduled flight.”