HOME > Chowhound > Home Cooking >


Sauteed onions and zucchini tasted like fish. Anybody else have this problem?

  • j

Oddly, cooking onions and zucchini this evening resulted in fishy smelling zucchini that we threw out. I've tried searching to see if anybody else has had this problem, but only found 2 posts of people making zucchini bread or zucchini muffins with a fish odor. I tasted the zucchini before cooking it and it tasted fine. It was organic and dark green. If anybody else has experienced this and has any idea why, it would be great to hear from you. I cook zucchini often and have never had this problem before.

  1. Click to Upload a photo (10 MB limit)
  1. Possibly the oil you sauteed it in. Possibly fish meal fertilizer was used by the farmer.

    1. since you said it tasted fine raw, i'm guessing it was either the oil or your pan. did you use canola oil by any chance?

      6 Replies
        1. re: ricepad

          +2 on that. Canola oil is nasty.

          1. re: ratbuddy

            +3 on the Canola. I don't even touch it anymore.

            1. re: rabaja

              +4 on canola being your problem. I used to have this problem once in awhile with canola. Now I usually by another neutral oil, or buy the smallest size available and throw it in the fridge when it gets hot.

              1. re: eight_inch_pestle

                Bought 3 pounds of zucchini and made several items with it. Stuffed zucchini with a sauce using oil, onions, zucchini, tomatoes and Ragu. Zucchini bread with canola oil in the recipe and a zucchini casserole using some oil. None of these items had a fishy taste.

        2. re: goodhealthgourmet

          To see so many here that have experience the fish taste of canola oil confirms my experience as well. Especially when used with high heat

        3. I used regular fat no salt butter. No Canola oil. Fish meal fertilizer is interesting, but none of the other zucchinis in the about 5 pack tasted odd. The frying pan was cast iron and I've never cooked fish in it.

          1. I've only ever used olive oil or butter to cook in this particular cast iron pan.

            1. What type of fat? How old, and how was it stored?

              edit: Oh, I see what you meant, butter. Was it sitting at room temperature for a long time, maybe went rancid?

              1 Reply
              1. I think you're on to something with the fish meal fertilizer. Just because they were all in the same pack doesn't mean they were all from the same plant. The butter used was good. The onions tasted fine cooked in the butter. Thanks for your ideas. I was contemplating whether it was the temperature the zucchini was cooked (not high enough), the method, or perhaps even the onion. But fish meal fertilizer makes the most sense.

                4 Replies
                1. re: JLCM

                  May well be the fertilizer. And as someone mentioned above, unsalted butter can go funky, especially if left at room temperature for too long this time of year.

                  Only other thought, now that you mention pan-type: have you cooked in the cast iron pan since then without problems? If the pan isn't seasoned properly the fat that keeps it looking glossy and beautiful can go rancid.

                  1. re: JLCM

                    I know next to nothing about gardening, but I do know that the traditional Native American
                    "three sisters" planting involved growing corn, beans, and squash (hard variety, I assume) in the same spot. The corn was a support for the bean vine, the beans provided nitrogen to the soil, and the squash shaded the soil, keeping in moisture. A fish was often buried in the planting mound as fertilizer. Sp just a guess that some farmers still put fish meal on squash.

                    1. re: JLCM

                      No, no, no. The only way fish meal fertilizer could possibly affect the flavor of vegetables is there was somehow residue on the zucchini and you didn't wash it off. When a fertilizer is applied to the plant, symbiotic bacteria break it down into nitrogen for the plant to use. No fishy component passes through.

                      Believe me, if plants absorbed the flavor of whatever they were fertilized with, humans wouldn't have been fertilizing fields with manure for thousands of years!

                      1. re: Karen_Schaffer

                        I did wash the zucchini, but I could have missed a spot. But you'd think the onions would have tasted bad as well, and they tasted fine. I appreciate everyones input. Thank You.

                    2. I have had my zucchini taste off if I don't get a good sear on the zucchini-- it tastes like a completely different dish. Do you usually sear it, and, if so, did you sear it less this time?

                      1. Yes. Usually I cook them until they are nice and toasty in color, a bit caramelized with the onions. But this time, dinner was ready, they were "cooked", not as long as I normally cook them, and decided they were done enough. Sometimes I will throw them in the pasta water and boil them. And other times I'll steam them. But mostly I cook them in butter.

                        5 Replies
                        1. re: JLCM

                          Yep. I have no scientific reason for why it causes an off taste, but it seems to. My money's on that.

                          1. re: jvanderh

                            Strange, eh? As a test, I could try to cook half of the 1 zucchini that's left just as I did before not browning them completely and partially steaming them with the butter and onions and the other half with completely browning them. If something fishy happens, I'll let you know.

                            1. re: JLCM

                              Please do! My thought is that some zucchinis (like most eggplants) are fishy, but a good sear either kills that flavor compound or distracts us from it. I'd be curious to know what you find out.

                              1. re: JLCM

                                I came upon this thread when I googled for exactly the same problem! I just reheated some zucchini latkes I made yesterday and I first noticed the smell in the batter. This is the second time this has happened to me, the first was in a zucchini spaghetti recipe that the next day reeked of fish. I'm a vegetarian, both zucchinis used were organic, have never eaten or cooked fish and the first time was in new york city in my mother's kitchen, steel pan, olive oil. And the second time was here in my apt in France. Teflon (which I hate) pan, again olive oil and the smell began in a mixture of potato, onion and zucchini-no oil, salt or acid added yet. I would love to know if you found out anything else about this.

                                1. re: tpoy

                                  I have found that some zucchini and patty pan squash have a light seafood esque taste to them. This usually occurs in the farmers market varieties I have encountered. The taste is fairly faint but I actually find it pleasant. Not sure why this is but it makes some sense when you consider the flavour profiles of some oysters have notes of cucumber, melon which are zucchini relatives.