The virus found in Catalonia is H5N8, said Meritxell Serret, in charge of agriculture in the northeastern region - the same one that has seen hundreds of thousands of ducks and geese slaughtered in France's southwest.
Up until now, the virus had only been detected in Spain in three wild animals.
The H5N8 strain can spread quickly in affected farms, often leading to the culling of thousands of birds.
Joan Guix, in charge of public health in Catalonia, sought to ease fears, saying it was a virus "that does not spread to humans."
Health authorities in Catalonia are now inspecting farms within a three-kilometre (1.9-mile) radius of the affected location to see if the virus had spread.
According to the World Organisation for Animal Health, 24 countries in Europe have detected the H5N8 virus this year, as have China, Egypt, Cameroon and India.