Originally Posted by Myates
I wouldn't consider pacing as a sign, as they don't pace... they just swim around. Some just have preferred routes.
Luckily, they don't get "bored" in the terms that we know it as- as they are fish and their minds don't work that way. It's if the tank is bare then they will hang around more then swim, if it's got a good amount of decorations, or if they have a neighbor, they will swim around often. Unsure about their memory span.. I remember a goldfish's memory span is only 3 minutes.
Goldfish have a much longer memory span than that. I think a study was done that determined they had the capabilities to remember things for a few months and could recognise individual faces out of a group of people. Mine are certainly intelligent enough to remember my face as they react with a lot more enthusiasm to me than to anyone else in the house.
I don't think its boredom fish suffer from, but a lack of stimulation. I had a female who lived in a sparsely decorated, bare-bottom tank and she would continually swim back and forth along the glass as there was nothing else really to do in there. That was definitely a neurotic behavior, as it was repeated over and over again even when I changed the decorations around and added a few hiding places.
I've found the less there is to do in a tank, the less active my bettas are unless I provide a source of entertainment for them. The bettas I house in small, bare-bottom tanks are much less active overall than those housed in more planted, and stimulating surrounds.
I think it is this lack of activity that causes stress and neurotic behaviour, rather than boredom as we know it.