A garage in Islington became a testing ground for a multi-million cocaine smuggling plot that killed thousands of tropical fish.

The lock-up in New Charles Street was used as part of a dry-run to import 17 kilogrammes of the drug, worth �1.6milllion, to the UK from Columbia.

Two Polish Men, Olaf Urlik and Norbert Jarzabek, planned to dissolve the cocaine into bags of fluid, which would be stored inside larger bags containing the fish.

To test the scheme, they imported a consignment of animals to Heathrow airport, which they took to New Charles Street and abandoned.

Emboldened by this success, they brought in 25 boxes of fish laced with drugs – but by this time the Serious Organised Crime Squad Agency (Soca) were monitoring the pair and arrested them at a house in Nottingham.

More than 16,000 fish had died, with just 34 survivors who are now alive and well at London Zoo.

The two men pleaded guilty to conspiracy to import cocaine, and were each jailed for 11 years at Nottingham Crown Court on Friday.

Gerry Smyth, form SOCA, said: “These two were exceptionally callous. They used living creatures as a test run and then effectively as packaging for their drugs, seeing only the profits they would make.

SOCA is grateful to the expert teams at ZSL London Zoo who helped us out in this very unusual case. Drugs cause misery for families and communities. These criminals are now facing lengthy jail terms and they’ve been denied their profits.”

Rachel Jones, form London Zoo, said: “Despite the awful way that they came about being here, we are pleased to say that the fish are now thriving at ZSL London Zoo’s Aquarium. When we first got the fish, most of them were drastically underweight, and they’d been living in cold, dirty water for days.”