Brittlegill that smells of herring: how to recognize it, photos

If a brittlegill smells of herring, shrimp or boiled crab, you're almost certainly holding a mushroom from the crab brittlegill group (Russula xerampelina), which foragers also call the herring brittlegill. Two more features give it away besides the fishy smell: the flesh and stem slowly turn brown wherever the mushroom is bruised or cut, and iron sulfate turns the flesh green. The cap can be purple, wine-red, rusty, brown or olive-tinged. It's edible, and in Europe it's prized as one of the tastiest brittlegills.

We came across these twice in autumn 2026: at the end of September in a broadleaf wood among fallen oak leaves, and at the beginning of October in a pine forest, in moss among lingonberries. The mushrooms looked nothing alike, yet smelled exactly the same, of herring. So, to be honest: this is probably the crab brittlegill group. You can't pin down the exact species from photos, and we explain why below.

How to recognize the crab brittlegill

Here's how foragers recognize the crab brittlegill and its close relatives:

• Smell: fishy, faint in young mushrooms and strong in old, dried-out ones, like boiled shrimp or herring.
• Cap: 5–15 cm, matte, convex at first, then flattening with a slightly sunken center. The color varies enormously, from purple and wine to rusty, brown or olive, and is usually darker in the center.
• Gills: cream at first, turning ochre and yellowish with age. Bruised spots slowly turn brown over time.
• Stem: white, often flushed pink or reddish, but it can be entirely white. Pressed, it slowly turns yellow, then brown.
• Flesh: white and brittle, slowly turning yellowish brown when cut. The taste is mild, not hot.
• Spore print cream, yellowish to ochre.

Here's the brittlegill from the pine forest, turned gills-up. The gills are still clean and cream, with no ochre tinge, so it's a young mushroom. The stem is straight and white, with no flush. None of our mushrooms had a pink stem, and that's normal: in this group it can be pink or white.

The cap: from purple to rusty

In this group, cap color tells you almost nothing. We found the first mushroom on 27 September in a broadleaf wood, among dry oak leaves. Its cap is purplish pink and matte, as if dusted, with bits of leaf stuck to it.

And here's October in a pine forest. This time the herring brittlegill's cap looks completely different: rusty red and smooth, with a few pale spots. Beside it lies a second brittlegill, turned over to show cream gills and a white stem with soil stuck to its base. If it weren't for our noses, we'd never have put these two finds in the same group.

The Latin name xerampelina comes from Greek and means “the color of dry vine leaves”. It fits: the cap really does mix wine, brown and yellowish tones, often in patches.

The herring smell: where it comes from

The fishy smell comes from trimethylamine, the same compound you smell in stale fish. In 2024 American chemists analyzed the air around fresh mushrooms of this group and found only trimethylamine and its oxide. It evaporates easily, so how strong the smell is depends on the mushroom's age and the temperature. A young brittlegill barely smells at all, while an old or dried-out one “stinks” out the whole basket. Scandinavian foragers suggest holding the mushroom in a warm palm for a minute or two to bring the smell out.

Here's that pair from the pine forest, with one brittlegill turned over to show its gills. This was the pair that smelled of herring. The cap is rusty red, and around it the moss is full of lingonberries and fallen pine needles.

Hence the Ukrainian name voniucha, “stinking”, which comes from old Ukrainian field guides; the folk name is blunter still: smerdiuk, “stinker”. Russian-language guides call the same brittlegill bureiushchaia, “browning”, after the flesh that darkens when cut. In fact the smell isn't repulsive at all but “seafood-like”, and experienced foragers track the mushroom down by it.

Browns when cut, turns green with iron sulfate

The second feature of the group is flesh and stem that slowly turn brown. Cut the stem and wait: the cut turns yellow first, then slowly yellowish brown. In our photos the stems are still white, so to see this you'll need to cut the mushroom and wait.

The third feature is open to anyone with iron sulfate, which garden shops sell. Mycologists say that all brittlegills of the Xerampelinae group turn green with iron salts. Here's how to check:

1. Dissolve a pinch of iron sulfate in a spoonful of water.
2. Drip it onto the cut flesh, or rub the surface of the stem with a crystal.
3. Wait a minute. On a herring brittlegill the spot turns dark green, gray-green or olive. Brittlegills from other groups don't give this green reaction.

We didn't run this test on our mushrooms, so you won't see it in the photos. But if you doubt your nose, iron sulfate gives a clear answer.

One name, several species

To the eye, the «crab brittlegill» isn't one species but a whole group, which scientists call subsection Xerampelinae. These fishy brittlegills are so variable that mycologists of the past described as many as 59 species and varieties of them in Europe. In 2024 an international team compared European and North American fishy brittlegills across several DNA regions for the first time and counted 17 reliable species on the two continents together, or possibly around 23 by another method. The researchers stress that telling them apart by appearance is very difficult.

Field guides traditionally separate the group's species by partner tree: Russula xerampelina proper goes with pine and conifer forests, Russula graveolens with oak. Interestingly, our purple brittlegill grew right among oak leaves. Here it is again, closer up.

Even so, there are no guarantees. A DNA analysis of soil and roots published in 2025 showed that many species in the group are less fussy than they seemed and grow with different trees. So for a forager it's simple: to the eye, the «crab brittlegill» is the whole group, and the exact species can only be pinned down under a microscope and by DNA. The good news is that in Europe the fishy brittlegills are considered edible.

Where and when to look

Brittlegills of this group form mycorrhiza with trees, so they grow on the ground in coniferous, mixed and broadleaf forests: in pine woods, spruce woods, under oaks. According to the international GBIF database, most of the Ukrainian records of both R. xerampelina and R. graveolens fall in September. Overall the season runs from late summer to October.

Our October pair grew in a classic pine-wood setting: in green moss under the pines, beside lingonberries. The caps are rusty red, and a dry leaf blown in by the wind lies nearby.

We found the purple September one on dry forest litter of oak leaves and blades of grass. It sat slightly sunk into the leaves, and we only spotted it because of its bright color.

What it can be confused with

The forest is full of red and purple brittlegills, but none of the hot-tasting ones smells of herring. Compare:

• The sickener also has a bright red cap and also grows in pine forests. But its gills and stem are pure white, it doesn't smell of fish, and it tastes very hot, like pepper. It's poisonous, causing nausea, vomiting and abdominal pain.
• The copper brittlegill, with its rusty-red cap, turns up in pine forests. Its flesh doesn't brown when cut; instead it turns gray, even black. It doesn't smell of fish.
• The hintapink has a red cap and likes damp, mossy pine woods. Its gills also turn cream-ochre with age, but its smell is indistinct, with no hint of fish.
• Russula integra has a brown cap with purple and yellowish tints, and old mushrooms have yellow gills. It tastes mild, but doesn't smell of herring.

The main rule for all brittlegills, covered in our article which brittlegills are poisonous: edible ones taste mild, dangerous ones taste hot. A fishy smell plus browning flesh tells you the mushroom belongs to the crab brittlegill group. If it doesn't smell and burns your tongue, leave it.

Is the crab brittlegill edible?

Yes. Ukrainian field guides from the 1970s rate it a good edible mushroom, and European mycologists count it among the tastiest brittlegills. It tastes mild, and the flesh stays firm and crunchy when fried. Scandinavians recommend stewing these brittlegills with dill in a sauce that brings out their “seafood” flavor.

A word about the smell: it doesn't disappear completely in cooking, and in old mushrooms it can be overpowering. So for the kitchen, pick young mushrooms whose smell is still faint. We boil these the same way as all brittlegills: 20–30 minutes once the water comes to the boil. There's more in the article how to clean and cook brittlegills.

And once more, in all honesty: we identified our group by smell, color and habitat, without the iron sulfate test or a microscope. That's enough for a photo, but before anything goes in the basket, check all three features together: the fishy smell, the browning flesh and the mild taste. Read more about the whole family in our guide brittlegill species of Europe.