How Intelligent Are Fish?

Have you ever heard the term "goldfish" used to describe someone with a bad memory? This comes from the myth that fish, particularly goldfish, have a three-second memory; but did you know this isn’t true? Fish are actually pretty smart! Check out some fishy facts below to see just how intelligent fish are.

Fish have a good memory

Contrary to the three-second memory myth, goldfish have memories that last for weeks, months, and even years, according to research! This has been supported by research for more than 60 years, too.

A 2014 article on fish intelligence talks about how fish demonstrate time-place learning, saying that they remember the hand that feeds them, the time of day, and even the place where the food is likely to arrive. If goldfish are fed just on one side of their tank, for instance, they will soon learn and remember to remain on that side of the tank at feeding times, whether or not they are fed. This phenomenon has also been seen in a variety of fish species like the poeciliids, galaxiids, golden shiners, and angel fish.

Fish can do math

A research team at the University of Boon has actually found that cichlids and stingrays can add and subtract! Recent research revealed that both fish species could add and subtract the number 1 simply in the range of numbers up to five.

Scientists from the University of Boon made use of colors — blue to add 1, yellow to subtract 1 — to train the fish. For example, the scientists would show the fish an image containing four blue squares, signifying addition. Two pictures, one with three blue squares and the other with five, would then be displayed. The fish would be rewarded if they swam to the image with the correct answer. With this method, the cichlids and stingrays learned that blue meant adding 1 and yellow meant subtracting 1.

Interestingly, even though fish don’t have a cerebral cortex which is a part of the brain typically responsible for performing complex tasks, these fish could still do simple math.

Fish have their own personality

Just like people, fish also have varying personality traits. Research has shown that these differences in personalities are influenced by genetic factors as well.

Fish can also react differently to a particular situation. For example, when put under stressful conditions, research has found that Trinidadian guppies reacted differently — some fled, some retreated after a while, while others weren't at all alarmed. Even more interestingly, their personalities were observed to be consistent even when the circumstances were different!

Fish can learn identities

Like other animals, fish typically establish rather permanent groups and get to know the members of those groups. For instance, guppies have no trouble remembering the identities of up to 15 individual fish! For fish to truly become familiar with other fish, it takes around 10 or 12 days.

Identities are important to fish because they use them to determine one another’s place in the hierarchy, and therefore predict others’ behavior in a given situation. Remembering each other is beneficial, too, as shoals made up of familiar individuals are more adept at evading predators than those made up of total strangers.

Fish also demonstrate a preference for familiarity. A study has found that if given the option of entering a tank with a large number of random fish or one with fish they have already seen, they almost always choose the latter.

Fascinating fish

Fish have shown intelligence in a variety of ways — in their good memories, arithmetic abilities, personalities, and social networks. Fish are complex beings, and their cognitive complexity is easily comparable to that of the majority of other animals. These clever creatures deserve some more love and respect!