Two men who tried to smuggle large amounts of cocaine into the U.K. in bags of live tropical fish were ordered jailed Friday for 11 years, BBC reported.

Olaf Urlik, 33, and Norbert Jarzabek, 32, both from Poland, admitted to conspiring to smuggling cocaine with a street value of $2.5 million (£1.6 million) from Colombia to Nottingham at a hearing in January, according to the report.

The Serious Organised Crime Agency, a British law enforcement organization, reported that the drug was dissolved in bags of fluid and stored inside larger bags with the live fish. More than 16,000 fish died in the operation. Thirty-four fish including stingrays, catfish and tetras, are recovering at the London Zoo Aquarium.

According to investigators, the two men carried out a trial run in April. They were eventually arrested in July, after picking up a shipment of 25 boxes of tropical fish, which SOCA had scanned and found 10 bags - weighing 37 pounds - of cocaine.

“This was a highly sophisticated operation," Nottingham Crown Court Judge Head said.

London Zoo’s Rachel Jones told SOCA the surviving fish are now thriving at the aquarium. "When we first got the fish, most of them were drastically underweight, and they’d been living in cold, dirty water for days."

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