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Claim check

Can fish feel you tapping on the glass?

ExaggeratedSomething true sits underneath, stretched well past what was shown.

They certainly detect it — a tap puts energy into the glass and the water, and a fish has two systems that read it. What has been stretched is everything after that. Nothing measures what a tap is like from inside a fish, and the gunshot comparison is invented rather than measured.

The claim as it circulates

“Tapping on an aquarium is deafening for the fish inside, because sound is magnified underwater.”

Where you may have met it: Aquarium signage asking visitors not to tap; Fishkeeping forums and pet-care advice; Widely shared explanations that tapping is like a gunshot to a fish

Taking it apart

What was claimed
That fish experience tapping on the glass as an extremely loud noise, often compared to a gunshot or an explosion, because sound behaves differently in water.
What was actually observed
Fish detect water movement through neuromasts — hair cells under a jelly cupula, on the skin and in canals beneath it — which respond to water being displaced within roughly a body length. Separately, the ear detects pressure waves travelling through the water. Blocking the lateral line chemically leaves hearing intact and removes schooling in the dark and obstacle avoidance, which is how the two were shown to be distinct systems. A tap on a tank wall produces both a vibration in the glass and a pressure disturbance in the water.
What the evidence supports
That a fish in a tank has ample means of detecting a tap, and that the near-field disturbance is exactly the kind of stimulus the lateral line evolved to read. Sound also does travel faster and further in water than in air, so the general intuition that a tank is not a quiet place is reasonable.
What it does not support
It does not support the specific comparisons. No measurement establishes what a tap sounds like from inside a fish, and loudness is a perceptual quantity that cannot be transferred between species by analogy. The "like a gunshot" figure has no source behind it. Detecting something and being harmed by it are separate claims, and only the first has evidence here — which is a reason to leave the glass alone, and not a reason to repeat a number nobody measured.

The rest of the answer

The claims underneath

Each one carries its own evidence, scope and caveats. Expand any of them to reach the studies.

Fish carry a row of receptors along the body that detects water moving nearby. Nothing touches them and no sound arrives — it is a sense with no human equivalent.

Established

Specialists would state this without hedging. Multiple independent lines of evidence agree.

The lateral line comprises superficial neuromasts responding to steady flow and canal neuromasts responding to accelerations, detecting near-field hydrodynamic disturbance on a scale of centimetres. Ablation impairs prey capture, schooling and rheotaxis independently of vision and hearing.

Who this applies to
Fishes and aquatic amphibian larvae.
Studied in
Actinopterygii, Amphibia
Why we rate it this way, and what the caveats are
EstablishedHigh confidence

Receptors identified, two functional classes distinguished, and behavioural deficits demonstrated by selective ablation across several species and tasks.

How far it can be extended

Neuromast anatomy and ablation effects are documented across many teleost families.

Caveats

  • The boundary between the lateral line and hearing is genuinely blurred in some fishes.
  • Pharmacological ablation may affect other hair-cell systems.
  • It is a near-field sense — centimetres, not metres.

Still unanswered

  • How lateral line and visual information are combined in schooling, where both are available and neither alone accounts for the behaviour.

Last reviewed 2026-09-02

The evidence (2 studies)

  • Supports · primary

    Lateral line system of fish

    Bleckmann and Zelick, 2009 · Integrative Zoology

    The synthesis of anatomy, the two receptor classes and the ablation results.

  • Context · supporting

    Hydrodynamic trail-following in harbor seals

    Dehnhardt et al., 2001 · Science

    The mammalian parallel: a different organ solving the same problem of reading disturbed water.

Go deeper

The lateral line

Not hearing. A fish’s lateral line reads the water actually being pushed aside — which is why it works within a body length and nowhere further.

Related things people ask

Last reviewed 2026-09-02