The young porpoise — which rescuers named Theo — was found stranded and in grave condition in Esquimalt in July.
Crews from the Vancouver Aquarium's rescue centre spent more than two months giving Theo around-the-clock care.
His even had to be supported in a special floating sling.
But Theo's recovery did not go as hoped and he died Wednesday night.
A necropsy will be performed at the provincial Animal Health Centre.
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