A nearly invisible oil spill threatens some of Asia's richest fisheries

Experts say there has never been so large a spill of condensate

A fiery collision that sank an Iranian tanker in the East China Sea a month ago has resulted in an environmental threat that experts say is unlike any before: An almost invisible type of petroleum has begun to contaminate some of the most important fishing grounds in Asia, from China to Japan and beyond.

It is the largest oil spill in decades, but the disaster has unfolded outside the glare of international attention that big spills have previously attracted. That is because of its remote location on the high seas and also the type of petroleum involved: condensate, a toxic, liquid