Sounds valid that. However, Honkytonk; I did see a young lad 'fishing' once; he caught a fish, threw it back, coupla minutes later he caught another, threw that back, this continued for an hour or so.. till his Dad observed that 'they' were all the same one dumb fish; size, markings, whole shebang. :-)

I strongly suspect that, with there being so many kinds of fish, that their memory spans can't all be the same. Also, there's meant to be an "electrical" short-term memory (e.g. swim forward, watch out for that rock, now the rock is behind me...) and the "chemical" long-term memeory (e.g. when that guy comes, food appears). It could be that a test was done to determine the electrical memory of some fish, and found that they have no idea what minor event just happened, but after a while they cotton on to simple patterns, or learn the position of hiding places and stuff.

Eels & salmon migrate because they remember the best holiday places.

It is true - several fish post the same questions on this website all the time.

Who's that girl in the Orange ad?
What's the music in the Lynx Advert?
Where can I go wingwalking?
Etc.

I know of a rather gruesome experiment in which goldfish gradually learnt their way around an underwater maze for food. Not only did they learn (and remember) it, but when their brains were fed to other goldfish, those goldfish learnt their way around the same maze faster. Gruesome like I said - but also proves some memory!

what was the question?