Fish Brains

Question
How big is a goldfish's brain?


Answer
Good morning Wilma, thank you for your question.

I thought I could find the answer to this question easily using Google. Especially since Dean Pomerleau's goldfish training article in National Geographic a few months back (I included a link below). It seems his website is now defunct, www.fish-school.com - how disappointing!

The best I can do for you is to say that an average goldfish brain weighs 0.097 grams, according to this site: http://faculty.washington.edu/chudler/facts.html

It seems like reliable information, especially since their sources were all sited just below the chart. What you should know is that brain size is not an indicator of intelligence:

"As you might imagine, larger animals have larger brains. However, this does not mean that animals with larger brains are smarter than animals with smaller brains. For example, a larger brain is necessary to control larger muscles in larger animals and a larger brain is necessary to process more sensory information from the skin in larger animals - this has nothing to do with intelligence."

This is from that same website, just a different page:
http://faculty.washington.edu/chudler/brainsize.html

If what you really want to know is - just how smart are goldfish, anyway? Then you may want to read this article, which suggests that goldfish are as smart as dolphins:
http://www.smh.com.au/news/world/flipper-flunks-goldfish-test--scientist/2006/08...

I wish I could tell you what percentage a goldfish's brain makes up of its body. That would really be more informative than telling you it weighs 0.097 grams on average. Betta owners all know (or can find out easily) that their pet's stomach is the size of its eye! I guess that I personally, will never know just how big (proportionately speaking) a goldfish's brain is, unless I volunteer at a high school biology class and dissect a goldfish for science.

Here's that NG article about training the goldfish:
http://news.nationalgeographic.com/kids/2006/02/trainfish.html

Here's a website devoted to goldfish, with goldfish expert Rick Hess on staff to answer goldfish questions:
http://www.goldfishparadise.com/

Let me know if you find a better answer. Have a good day!
Nicole