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 a
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 fertilize in the water.
In principle, there could be a word for a female fish with egg development, but none is listed in any
proper dictionary.