text: where does the phrase "but thats another kettle of fish" come from?   we still do have fish kettles in britain.  they are long oval pans which can sit across two burners - big enough to take 'the one that got away'!    they have lids, and my stepmother's is a pretty fish kettle as it is shiny stainless steel.  perhaps the phrase comes about because one thing you would never do is cook two different types of fish in the same kettle as their flavours would taint each other.  each has to be cooked (considered) separately.