What has a three-second memory?

Not a goldfish, for starters.

Despite its status as a proverbial fact, a goldfish’s memory isn’t a few seconds long.
Research by the School of Psychology at the University of Plymouth in 2003 demonstrated beyond
reasonable doubt that goldfish have a memory-span of at least three months and can distinguish
between different shapes, colors and sounds. They were trained to push a lever to earn a food
reward; when the lever was fixed to work only for an hour a day, the fish soon learned to activate it at the correct time.

 A number of similar studies have shown that farmed fish can easily be trained to
feed at particular times and places in response to an audible signal.

Goldfish don’t swim into the side of the bowl, not because they can see it, but because they are
using a pressure-sensing system called the lateral line. Certain species of blind cave fish are able to
navigate perfectly well in their lightless environment by using their lateral line system alone.
While we’re dealing with goldfish myths, a pregnant goldfish isn’t, hasn’t and can’t be called a
‘twit’. Goldfish don’t get pregnant: they lay eggs that the males fertilise in the water.

In principle, there could be a word for a female fish with egg development – such as ‘twit’, ‘twat’or ‘twerp’ – but none is listed in any proper dictionary.

STEPHEN Well, there is this fallacy that goldfish have a three-second memory –
ALAN It’s not a fallacy!
STEPHEN It is a fallacy. They've done tests.
ALAN Oh, they haven’t.
STEPHEN They have. A man from Plymouth University did a wonderful test –
ALAN There isn’t a Plymouth University; that’s made up.
SEAN It’s just a sweet shop with a copy of The Times in it.