Since this is my first post, I want to discuss fish memory, which is where I got the title for the blog: >3s (greater than 3 seconds). This comes from the myth that fish only have a 3-second memory, recently reinforced by the character of Dory in Disney’s Finding Nemo (and its sequel, Finding Dory). I haven’t been able to find the origin of the 3-second memory myth, but people that keep fish have known it to be false for a very long time. In 1883, Hugo Mulertt wrote The Goldfish and its Culture, which first popularized home aquaria (he also founded and owned the magazine The Aquarium, marketed his own line of fish food, and translated a book of German fish recipes to increase Americans’ consumption of fish). Mulertt had this to say:
“Goldfish have a good memory; they will soon learn to know their master, remember their
feeding-place and time. They can be trained to good manners, as they are easily influenced
by their surroundings, and good qualities of individuals can be perpetuated in their
Ok, so he wasn’t so strong on how genetics works.
The kind of memory Mulertt mentions, learning when, where, and by whom they are fed, is the most common type of learning demonstrated in fish, and there are plenty of examples of it. Rainbow trout can remember that pressing a bar leads to food even after not seeing the bar for 3 months ; goldfish may remember a color that was paired with food for almost a year ; and one researcher who trained common rudd to eat out of his hand found that they would still eat of his hand (but not anybody else’s) after not seeing him for 6 months .
Some of the more impressive feats of fish memory involve spatial learning. Salmon, returning from a few years of adventure on the high seas, can identify the exact stream where they were spawned by its unique odor . It smells like home. However, you can only smell which stream is home when you are already in the right river system. How do you get from the middle of the Pacific to the right river-mouth? Salmon, it seems, can use variations in the magnetic field of the earth to achieve this, which means they have to also remember what the strength of the field was at the mouth of the river when they left home, several years ago .
So why do people think that fish only have a 3-second memory? I can only speculate, but it might have something to do with the small round aquaria that goldfish are often kept in (like Elmo’s pet goldfish Dorothy, from Sesame Street, watched by millions of impressionable two-year olds). Maybe a child asked whether the fish get bored in so small a space and some well-meaning adult came up with the meme, little realizing how it would spread. I guess the moral of this is: when lying to children, keep in mind that they have memories every bit as good as the average goldfish.