Coming back to the quintessential Bengali fish curry, Tel Koi, there is again another detail worth sharing. I have a humble collection of food-related books and that includes a Bengali cookbook by Tripti Dasgupta. The lady wrote about her experience with Tel Koi there. She wrote there, Tel Koi is not about Koi fish curry loaded with Oil (mustard Oil in this case)! According to her The "Tel" in Tel Koi is actually the oil that secretes from the fish itself! I found this information really interesting. In fact, upon reading her book, I started checking the Koi Mach whenever I cook whether it is secreting oil or not! I found it actually is true! Whenever the fish is fresh enough it secretes oil!