Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Question on memory in small fish

  1. Jul 8, 2003 #1
    I've heard it said that small fish, like you would keep in an aquarium, only have a few seconds of memory. If this is true, why do they develop patterns of behavior?

    I have two small fish one of them is a Red Molly (I think that is the name) that has developed certain habitual resting areas in the tank. If it has no appreciable memory, does it discover these places anew each time? Or do you think that research may be wrong about the memory of small fish?
  2. jcsd
  3. Jul 8, 2003 #2
    Maybe. Why don't you do some type of memory experiment on your fish?
    Surprise the fish somehow every x seconds and see if it acts surprised.
  4. Jul 9, 2003 #3
    well it's times like these i wish i cared about pychology, but from my limited knowledge and the thinking that insued i have come to certain conclusions...

    i was having this exact discussion the other day and i agree that fish like all animals have the ability to 'learn' through conditioned response, ie if it sees you coming with a cylindrical container it will think 'mmm, food' becasue every time the visual part of it's brain processes 'human, cylinder' it's food (?) brain ends up happy. just like all other animals your fish also has some already learned reflexes, like resting in certian areas, say in a protected place to avoid predators. so i reckon a fish's behaviour can be entirely attributed to these types of memory, genetic and conditioned. but then there's the 'other' memory which is what i think people are refering to, i don't know how to classify it (like i said stuff pychology) but i have worked out a way of testing it, say you put something 'desirable' to the fish behind a screen (umm, another fish? food?) but in a tank next to the one your fish is in, so it can't get to it, wait 5 seconds then put your fish in that tank, will it go behind the screen with a horny look of anticipation on its face?

    i think not, try it out, i don't own any fish
  5. Jul 9, 2003 #4
    It sounds like you are thinking that it is more of a habit than memory. This is possible.

    I have to develop habits for certain things such as placing my keys in the same place all of the time when not in my pocket, or my glasses when I'm not wearing them, or else I will forget where I have left them.

    Thanks for the responses.
  6. Jul 9, 2003 #5


    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    I doubt fish are limited to a few seconds of memory in all things. I have not read any research on fish memory, but I used to have aquariums and did a lot of reading about fish behavior.

    As an example, many fish are territorial (including some "small fish" you might keep in a home aquarium) and they use landmarks to identify their territory (rocks, logs, plants, etc.). One trick when introducing new fish to a tank is to rearrange all the ornaments in your tank so no fish has an established territory (otherwise the newbie gets beaten up when it tries to find a hiding place in someone else's turf).

    Another example, I've read anecdotes of fish that remember their owners (i.e., they swim calmly in the presence of their owners but hide away when anyone else enters the room).

    Anyway, I'm sure the degree of fish memory/intelligence depends on the species. (I also have the impression that salt water fish have more brain power than fresh water fish.) I would think that mollies are toward the lower end of fish intelligence.

    These are just my impressions...don't quote me on this!
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook