Twelve pufferfish facts, fact-checked
Pufferfish are slow, poorly armoured and almost impossible to eat safely — which is the point. Full profile in our pufferfish guide.
1. Tetrodotoxin is far deadlier than cyanide
It blocks sodium channels in nerves, causing paralysis while the victim remains conscious. There is no antidote.
2. The toxin comes from bacteria
Acquired through diet, which is why pufferfish raised on controlled feed can be non-toxic.
3. They inflate with water, not air
A highly elastic stomach fills rapidly, and the fish becomes too large and awkward to swallow.
4. Inflating is costly
It is a last resort, exhausting and stressful, which is why handling a puffer to make it inflate is genuinely harmful.
5. They have no ribs or pelvic bones
Removed by evolution to allow the stomach to expand.
6. Teeth are fused into a beak
Four fused teeth crush shellfish and crustaceans, and grow continuously.
7. Some build geometric circles
Male white-spotted pufferfish construct intricate patterned circles up to 2 m across on the seabed to attract females — the source of the 'underwater crop circles' mystery.
8. Fugu preparation is licensed
In Japan, chefs train for years and are licensed to prepare pufferfish, because the toxin concentrates in specific organs.
9. Poisoning is untreatable directly
Treatment is supportive — ventilating the patient until the toxin clears.
10. Some live in fresh water
Several species inhabit rivers and lakes in Africa, Asia and South America.
11. They are agile, not fast
Manoeuvring precisely with pectoral, dorsal and anal fins, sacrificing speed for control.
12. Status varies
Most species are not currently threatened, but overfishing for the fugu trade, habitat loss and aquarium collection affect particular species.
Read the full pufferfish wildlife guide for IUCN status, population context and sources — or donate to WARN to help fund the partner teams protecting wildlife on the ground.
