Despite lacking eyes, a mouth, and part of its brain, the goldfish swam around as if nothing had happened. It didn’t crash into walls. It didn’t float lifelessly. It simply carried on headless, but somehow alive.

According to the owner, the bizarre condition began when tissue on the fish’s head turned necrotic, likely due to infection or poor water quality. As the dead tissue decayed, other fish began pecking at the wound, accelerating the damage until the goldfish’s head was almost entirely gone.

And yet, for nearly two weeks, it lived.

How is that possible?

As shocking as it sounds, fish anatomy makes this survival story biologically plausible. Unlike mammals, whose brains are compact and head-contained, goldfish have a more linear brain structure. Crucially, the brainstem which controls basic life functions like breathing and heartbeat is located deeper in the body, near the spine. So while the fish had lost its sensory functions and much of its brain, its life-support system remained intact.

Even more fascinating, swimming doesn’t require brain commands. Automated neural circuits in the spinal cord manage that task. Plus, fish have a line of pressure-sensitive sensors along their sides like biological sonar enabling them to sense and avoid obstacles, even blind.

In the end, the goldfish’s undoing wasn’t the loss of its head, but a fatal electrolyte imbalance. With such a massive wound, freshwater poured into its bloodstream unchecked. Despite surviving the unimaginable, the internal damage was too great.

It swam headless through life for nearly two weeks. A bizarre miracle of nature and a reminder of how much we still don’t understand about life’s limits.