One of my favorite grilled fish is the Blackspot seabream

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Unfortunately, now and then, the belly part of the grilled fish tastes slightly bitter and smells a bit, which makes me not to eat those parts (quite a waste).

Does this come from not cleaning/preparing the fish properly or, as I've been told by a local fish-restaurant owner, is this caused by the pheromones of the fish during certain times of the year?

2 Answers 2


From what I've been told, the bitterness around fish belly is caused mainly by spilled bile when the liver or gallbladder is punctured.

May be caused by improper handling, packaging, rough treatment, excessive pressure (too much weight during storage or transportation), or careless cleaning procedure.

Improper cleaning or removal of the guts may also play a secondary role, though I suspect bile to be the main culprit.

You can some times tell in advance if you notice mustard-yellow spots in the inner walls of the fish belly before or cooking, which tend to turn silvery-greenish after cooking, caused by the spilled bile tainting the meat.

These are usually a indication of bitterness.

You can see an example around the area where the finger is touching the fish. You can see an example around the area where the finger is touching the fish. Image source

Food source of the fish may also play a significant role in belly taste.

I have noticed that aquaculture or farmed fish tend to have little to no bitter taste at all, as opposed to wild or free range ones, possibly due to different feeding habits. Farmed ones likely exclusively eat the provided feed (with controlled selection of ingredients for taste and growth), rather than whatever they can naturally find in their environment.

Specifically addressing the pheromone as a cause, I've never personally heard about it, but pork does get Boar Taint (which is pheromone based effect on taste), so it is not totally beyond the realms of possibility, thought I'd expect it to have a widespread effect of fish as well, rather than just around the belly.

I have recently had fresh grilled wild White Seabream (Sargo) and it is one of the worse fish in terms of bitterness, which contrasts strongly with the aquaculture Gilt-Head Bream I can buy at the same vendor, and has absolutely no bitter taste, supporting my food source hypothesis.

  • 1
    I still wonder if pheromones could be the reason, as I buy the fish at the local fish-market and they really know how to clean the fish (doing it for a life-time)
    – Vickel
    Jan 3, 2021 at 0:24
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    Never heard about the pheromones, I'd expect those to be present in the fish as a whole, not just the belly area, but it is possible. I generally buy fresh fish from a local super market where the staff ladies are also experienced cleaners, but spilled bile is quite frequent if not the norm. Maybe they are just careless. Just grilled wild white seabream (sargus) a few hours ago for dinner, bellies were quite bitter. One of the worse fishes in terms of bitterness even with proper cleaning Jan 3, 2021 at 0:33
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    yes Sargo (seabream ) and Besugo (Blackspot seabream) are definitely some of the worse in that bitter aspect. The reproduction part of a fish is also in the belly area, and as I was told by a local fish-restaurant owner, I continue to wonder if there is such thing as smell/taste caused by pheromones.
    – Vickel
    Jan 3, 2021 at 0:40
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    I found this article, but it doesn't reflect if pheromones would change the belly taste of the fish when the fish release it in their mating season. BTW, your image shows a "GROSS" failure in cleaning the fish and someone must have left it in a fridge for a day or so in order to get this color. YAK
    – Vickel
    Jan 4, 2021 at 0:06
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    Well for what is worth pork does get Boar Tain which tastes quite awful, so it is not a totally absurd idea, but it is a widespread taste. Jan 4, 2021 at 0:50

When preparing whole fish at my household, we always slice open the stomach and use a pair of kitchen scissors to snip and remove its guts. We also rinse out the inside of the stomach after removing the guts.

I believe the reason the belly region of your fish tastes bitter is because of un-finished cleaning, just like your local fish-restaurant owner says.

  • 3
    Usually bitterness comes from the gallbladder if punctured while removing the internal organs, because fish bile is extremely bitter.
    – mbjb
    Jan 2, 2021 at 2:55

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