Do Goldfish Have Brains Or Are They Brainless?

Last Updated on December 7, 2021 by cmoarz

We’ve all heard the saying “memory of a goldfish”, generally used as a light-hearted insult. But what is a goldfishes memory really like? For that matter, do goldfish have brains?

The answers might surprise you!

Do Goldfish Have Brains?

Goldfish do have brains! A very tiny goldfish brain size that only weighs 0.097 grams. It resides above the eyes at the top of the head. The attention span of a goldfish is a solid 9 seconds, But their memory span is up to 5 months or longer.

Internal Goldfish Diagram Including Brain

Diagram sourced from

Certainly not as impressive as the human brain, But this fish brain does exist. And because of this efficient little fish brain, Fish learn to do some incredible things.

In fact, Training goldfish is almost as easy as training any other animal. With the use of positive reinforcement (food and treats), it’s been shown that goldfish are very easy to train to do all sorts of incredible things. Fish learn quickly too.

Goldfish trained properly can eat out of your hand, rollover, Go through a hoop, they can even be trained to play soccer!

That wouldn’t be possible without a brain and a good memory.

Video of goldfish playing soccer trained by a man in China

Do Goldfish Have Thoughts?

Goldfish can think. But what do goldfish think about? That’s a great question. Goldfish have been shown to have strong social learning skills, can tell the difference between different humans, and map out their underwater environment.

As far as what a goldfish brain might be thinking, it is a bit out of what we can measure. But we can safely assume its thinking process is going to be a lot like high order vertebrates such as primates, according to the research we have done.

This means they think about danger, predators, safety, Food, Procreation. Given how social the goldfish is and its ability to follow schooling and other fish behaviors, we can assume they also think about friends and family.

This also means goldfish can actually become lonely after the loss of a tank mate. With that said, Interestingly enough goldfish display no paternal instincts and will eat their young and their eggs. Very strange behavior all things considered.

How Many Braincells Does A Goldfish Have?

Not many fish have had the neurons in their brains counted, however, an adult zebrafish has been counted at ~10,000,000 neurons and a goldfish should be fairly similar.

To give you an idea of comparison, the human brain contains 100 billion cells. That’s several orders of magnitude larger than a goldfish!


Owner of and also owner of actual Aquarium Gravel believe it or not! ;). Setting up beautiful aquarium sceneries and habitats since I was very young. Enjoy!