People often talk about “having the memory of a goldfish” to mean they’re forgetful, so it’s understandable that people think goldfish are unintelligent and wonder whether goldfish have brains at all.
And it’s certainly not a silly question. Did you know that not all animals do have brains?
For instance, starfish have a complex nervous system, but not a centralised brain. While jellyfish don’t have a brain or a central nervous system. If these aquatic creatures don’t have brains, maybe goldfish don’t either? Let’s find out…
Do goldfish have brains and how intelligent are they really?
You might be please to hear that the answer is yes – goldfish do have brains.
This diagram shows the location of a goldfish’s brain. As you can see, the brain is located at the top of the head, above the fish’s eyes, at the front of its spine.
And not only do goldfish have brains, they’re actually quite intelligent animals.
It’s myth that goldfish have bad memories. They can actually remember things for several months, at least.
Goldfish can also be trained to do tricks and behave in certain ways. For instance, pressing a button to get food. Goldfish wouldn’t be able to do this if they didn’t have a brain and at least a basic form of memory.
Goldfish are also socially intelligent. They are able to recognise and remember individuals – including humans – and they change their behavior around mates, potential mates and fish they know to be aggressive.
How big are fish brains?
While goldfish do have brains, their brains are not exactly huge!
A goldfish’s brain is about the same size as its eye. When you compare that to a human brain, you’ll realise that – proportional to their body size – the goldfish brain is really quite small.
This is the same for most types of fish. Most fish have brains that are about 1/15th the size of a similarly-sized mammal or bird.
In fact, it is a fish that holds the record for the lowest ratio of brain size to body mass. The Bony-eared Assfish not only has a very unfortunate name, it also has the smallest brain (relative to its size) of any animal with a spine (vertebrates).
There are some exceptions though. Elephantfish and sharks actually have quite large brains for their body size – about the same as birds and marsupials.