Off Japan, researchers watched male pufferfish about 12 centimetres long spend 7–9 days building seabed circles about 2 metres wide with their fins and bodies. They decorate the ridges with shell and coral fragments.

These courtship nests attract females, and spawning happens at the centre. The shape helps gather fine sand there. After spawning, the male tends the eggs as the circle erodes; in the study, males built fresh nests for the next breeding cycle.

A Tiny Fish’s Enormous Dating Profile

Completed pufferfish courtship nest; scale bar 30 cm (Figure 1H) — Hiroshi Kawase et al., Fishes (2017), Figure 1; CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Panel extracted from the paper.

Pufferfish nest during construction; scale bar 30 cm (Figure 1F) — Hiroshi Kawase et al., Fishes (2017), Figure 1; CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Panel extracted from the paper.

Photographs and construction trajectories of a pufferfish nest (Figure 1) — Mizuuchi et al., Scientific Reports (2018), Figure 1; CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/).

A Tiny Fish’s Enormous Dating Profile

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