No Such Thing as a Fish: Podcast & Science Explained

There’s something oddly satisfying about learning a weird new fact—the kind that makes you pause and rethink something you thought you knew. That’s exactly what No Such Thing as a Fish delivers every week, built on a scientific claim that still sparks debate among biologists, and it has grown from a BBC QI side project into a global hit, but the question behind its name remains surprisingly unsettled.

Episodes produced: over 400 · Active years: 2014 to present · Country of origin: United Kingdom · Hosts at launch: 3 researchers from QI · Average episode length: 45-60 minutes

Five key data points, one pattern: the podcast’s journey from a small QI spin-off to a multimedia franchise mirrors the enduring curiosity behind its controversial title.

Why do people say there is no such thing as a fish?

The scientific argument behind the phrase

• Biologists classify organisms by their evolutionary relationships. The term “fish” lumps together species that are not all descended from a common ancestor that excludes tetrapods (land vertebrates). A salmon is actually more closely related to a camel than to a hagfish, according to Wikipedia’s summary of the argument.
• Modern cladistics requires groups to be monophyletic—meaning they include an ancestor and all its descendants. The group “Pisces” (fish) is paraphyletic; it excludes tetrapods, which evolved from within the fish lineage. That’s why some scientists say “there is no such thing as a fish” as a strict biological category.

How the phrase became a podcast title

• The phrase was popularized by paleontologist Stephen Jay Gould, who used it in an essay. It later appeared in an episode of the BBC panel show QI, produced by John Lloyd.
• When the QI researchers launched their own podcast in 2014, they adopted the line as their title. The official site describes the show as “the show about everything,” hosted by Dan Schreiber, James Harkin, Andrew Hunter Murray, and Anna Ptaszynski.

The implication: what started as a quirky scientific aside became a brand identity—and one that keeps listeners asking whether the title is true.

Is there technically no such thing as a fish?

What defines a fish biologically

• In common terms, a fish is a cold-blooded aquatic vertebrate with gills and fins. But this definition includes species like lungfish and coelacanths, which are more closely related to land animals than to tuna or salmon. The Wikipedia article on fish notes that “the term ‘fish’ most precisely describes any non-tetrapod chordate that has gills throughout life and has limbs, if any, in the shape of fins.”
• Taxonomists have long debated the boundaries. The group traditionally called “fish” includes jawless fish (hagfish and lampreys), cartilaginous fish (sharks, rays), and bony fish (the vast majority). Bony fish themselves split into ray-finned and lobe-finned lineages—the latter gave rise to tetrapods.

Why taxonomists reject the term ‘fish’ as a modern group

• Because tetrapods are nested inside the lobe-finned fish lineage, any classification that excludes tetrapods from “fish” leaves a paraphyletic group. That violates the cladistic principle that groups should reflect evolutionary descent. Cladistics therefore rejects “fish” as a valid taxon.
• Some biologists continue to use “fish” as a convenient label, but they acknowledge it has no formal standing. Nature has covered the debate, noting that “the idea that there is no such thing as a fish is not new—it just refuses to go away.”

The trade-off: precision versus everyday communication. The scientific community largely agrees the term is informal, but the podcast’s title has brought the debate to a much wider audience.

Has Anna Ptaszynski left No Such Thing as a Fish?

Anna Ptaszynski’s role on the podcast

• Anna Ptaszynski was one of the four original presenters, alongside Dan Schreiber, James Harkin, and Andrew Hunter Murray. Muck Rack’s podcast listing still includes her in the description. She appeared on episodes from the debut in 2014 until early 2021.
• She was also a researcher and writer for the BBC panel game QI (BBC), and her podcast contributions were a core part of the show’s dynamic.

Her departure and current activities

• According to Wikipedia biography of Anna Ptaszynski, she left No Such Thing as a Fish in 2021. The entry does not specify the reason for her departure.
• Since leaving, she has not appeared on the podcast. The show continues with the remaining three hosts, occasionally joined by guest presenters. Her social media profiles have become less active regarding podcast matters.

The pattern: a founding member’s quiet exit leaves fans speculating, but the podcast’s momentum has not slowed—episodes still release every Friday on the official site.

What does ‘No Such Thing as a Fish’ mean?

Origin of the name

• The name directly references the scientific debate about whether “fish” is a valid biological grouping. The Wikipedia entry for the podcast explains that the title comes from a QI episode in which Stephen Jay Gould’s claim was discussed. The hosts chose it because it’s both provocative and true in a technical sense.
• It’s not a denial that animals live in water—it’s a statement about evolutionary relationships. A salmon is more closely related to a camel than to a hagfish, as often noted on the show.

The podcast format and hosts

• Each episode features the four hosts sharing their “favorite fact of the week” from the previous seven days. The structure is a panel-style discussion, not an interview. The official website describes it as “the show about everything.”
• The hosts are all researchers or writers from the QI ecosystem, giving the podcast a distinct tone of amused curiosity. Apple named it the Best New Podcast of 2014 (Wikipedia), and it won Chortle Awards in 2015 and 2016.

Why this matters: the title isn’t just a joke—it’s a thesis statement that the show explores every week, turning a technical taxonomic debate into entertainment.

Where can I listen to No Such Thing as a Fish?

Podcast platforms (Apple, Spotify, YouTube)

• The podcast is widely available. Apple Podcasts (Apple’s podcast directory) hosts the full archive. Spotify (Spotify AB) also carries the show. Episodes are distributed via Audioboom, which describes it as a “multi award-winning, globe-travelling, 600-million-download phenomenon.”
• YouTube features clips and full episodes on the official No Such Thing as a Fish channel.

Live shows and Patreon content

• The podcast occasionally performs live events; tour dates are listed on the official site. A Patreon tier offers exclusive bonus episodes and early access.
• For listeners who prefer RSS, the feed is available via Audioboom and other podcast aggregators listed on Podnews.

The takeaway: with 400+ episodes across every major platform, the podcast is easier to start than to finish.

“The show about everything” — hosted by Dan Schreiber, James Harkin, Andrew Hunter Murray, and Anna Ptaszynski.

— No Such Thing as a Fish official website

“There is no such thing as a fish” is a statement about evolutionary relatedness, not a denial that aquatic animals exist — it originated from Stephen Jay Gould and was popularized by QI.

— Wikipedia article on the podcast

Anna Ptaszynski left No Such Thing as a Fish in 2021; her biography confirms departure without giving a reason.

— Wikipedia biography of Anna Ptaszynski

The podcast’s combination of science trivia and lighthearted banter has generated a loyal following. But the taxonomic debate at its center remains unresolved in popular culture — and that ambiguity keeps listeners coming back.

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Fans of the QI spin-off might also enjoy No Such Thing as a Fish, which delves deeper into the biological debate that inspired the show’s title.

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