Individual clown anemonefish shrink to survive heat stress and social conflict

Heatwaves cause clownfish to shrink — a surprising survival strategy
Science Advances (2025) — Melissa Versteeg, Chancey MacDonald, Morgan Bennett-Smith, Peter Buston, and Theresa Rueger

This study revealed that clownfish (Amphiprion percula) can shrink in size to survive extreme marine heatwaves — the first documented case of shrinkage in a coral reef fish.

Conducted at the Mahonia Na Dari Research and Conservation Centre in Papua New Guinea, the team monitored 134 individually marked clownfish through a 2023 heatwave and found that 75% of them became shorter as temperatures rose. Shrinking increased their likelihood of survival by up to 78%, suggesting that this physiological flexibility may provide a short-term buffer against warming oceans, albeit with reproductive tradeoffs. The work was widely covered by international media, including CNN, Washington Post, and NPR, and has been featured in over 200 news outlets worldwide.

Link to paper: https://www.science.org/doi/10.1126/sciadv.adt7079