Guys, where do you think this cafeteria is? MOST of them are usually not located down the hall, round the bend, up the stairs, down that chute and at the end of the drainage canal.
They are usually just a little ways off from the workplace and, eventually, any smell there will gradually make its way out to the workspace.
Fish, in general, is tasty. I like it, and love a good garlic trout or teriaki(sp) salmon. But I also know that it DOES stink, and is quite invasive, when reheated. While you may not have a choice in what you have packed for lunch and occasionally have something like this, you must also know that MANY people find this rather off-putting.
It does not matter what YOU think in cases like this. There are many practices you may find foolish but others find invasive, or even offensive, especially in the workplace. If those acts are not critical to the operation of the buisness (I don't know, like a born again Christian being a bartender at a strip club.... being offended by nakedness is not exactly a good combo there...) then it is usually beneficial to the company to try and avoid stuff that will cause friction....
You are ALLOWED to bring in fish to work, but just know that you ARE pissing people off, no matter what you think. Try to be gracious about it, try not to do it often, and apologize for the smell if someone raises an issue. After that, that is all you can do. If they try and take it further, break it off and be done with it.
BTW, when I said apologize, I meant in a sincere manner, not a "i am SORRY you don't like it when other people EAT around here!!". Trying to be considerate of co-workers is always a good thing.