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Can Koi Recognize Themselves in a Mirror?

Fish Self AwareDo fish recognize themselves in the mirror?

A study released in February 2019 suggests they might, leading scientists to wonder if fish are self-aware.

The potentially groundbreaking news comes from the Germany-based Max Planck Institute for Ornithology and Osaka City University in Japan. Researchers from the two institutions placed mirrors outside the aquarium glass of several cleaner wrasse, a type of fish that lives in coral reefs. They then dotted their throats with brown marks – which the fish tried to remove after apparently seeing them in the mirror.

So what does this discovery mean for our pond-dwelling koi, goldfish and catfish? Maybe nothing – or maybe a lot.

The researchers in this study were performing what’s known as the mirror test, a method scientists started using in the 1970s to determine whether animals are self-aware. Humans can pass the mirror test by the time they are about 2 years old, as can certain primates and a few other species.

The researchers in the cleaner wrasse study determined that their fish had, in fact, passed the mirror test.

What this outcome means has sparked some controversy in the scientific community. Even the study’s authors have questioned just how to interpret the results. Did the fish seem to recognize themselves in the mirror? Yes. Does that mean they have a sense of self in the same way a human or even orangutan does? That’s harder to say.

At Splash, we don’t have any answers to these big questions. All we know is that our koi are pretty darn smart. Just watch how they swarm to the edge of the pond whenever someone approaches with treats.

For now, we’ll keep counting down the days until spring, when we can have these fun interactions with our fish again. We’ll leave the philosophy to the scientists.

Read more about the study here.