Why is it so easy to kill a fish? Why does no one cry when they see pictures of shoals of fish being scooped out of the ocean onto a trawler? Why does a travel magazine that takes you through a fish market which hundred of corpses lying about not bother you? How can you go to a restaurant and choose a live fish in a tank to be served to you fried? How can people keep aquariums in public places and treat the fish as if they were just gaily-coloured moving ornaments.
Is it because you do not think they are intelligent or have any emotions?
Many people ask me whether fish show any sign of intelligence? Are some smarter than others? Could most of them take a college exam and score about as high as your average adolescent? The answer to the first two questions is an unequivocal “yes”. The last question will have to wait until fish are allowed into college.
Although fish definitely show signs of intelligence, measuring intelligence is not easy. The problem is that often the questions we ask of animals hold little meaning for them like trying to train your pet rat to remember its name. Why should it?
You’re going to feed it anyway. On the other hand, it has escaped many who think that animals have less intelligence than them that their dogs respond to several languages and sometimes just a mere small gesture – which is more than a lot of humans I know.
Biologists generally agree that an animal’s ability to learn serves as a measurable criterion for intelligence. There are different types of learning. Just because an animal lacks proficiency in one type of learning doesn’t doom it to mental mediocrity across the board. We see the same thing in humans. I am hopeless at maths and learning languages, but I can pick up and remember thousands of facts that I need to know.
So do fish learn? Absolutely! One clear example is their ability to quickly learn spatial arrangements. Non-schooling species, and sometimes even schooling species, often establish home ranges where they focus most of their daily activity, much like teenagers hang out at the local cinema. Some species even establish territories – areas that they defend against either all intruders or members of their own kind. Obviously, in order for these fish to recognize home ranges they have to first learn to differentiate “home” from “non-home.” That, in turn, entails learning where the boundaries lie; learning that one rock falls within the range, while another doesn’t.
But perhaps the most crucial measure of intelligence, and one we humans place a great deal of value on, is associative reasoning. This means the ability to learn relationships between objects or events and then applying those relationships to novel situations. Fish species are definitely capable of associative reasoning.
Take, for example, the results of recent memory tests on largemouth bass at the Pure Fishing Fish Research Centre. In these tests wherein a group of six bass were free to strike an artificial minnow for as long as they pleased, they realised after several fruitless attempts to eat the artificial minnow, that it was faked and abandoned their attacks. In other words, through their failure to get a food reward, the bass quickly learned to ignore what looked like food.
Two weeks later the same bass were shown a second artificial minnow, similar in shape but easily distinguishable from the first. The bass ignored the second minnow, although another first time group of bass pounded away at it just like the first group did on the original minnow. Clearly the experienced bass remembered their wasted efforts from the first time around and transferred that knowledge to an object they had never seen before.
So how long did the bass retain their memory? Every single time for months afterwards. The scientists believe that they bear the memory of their experience for the rest of their lives. That is intelligence.
If you narrowed down human responses to everything, they would basically fit into the classical “fight or flight syndrome”. When you eat, when you love, when you converse, what you want, what you reject – everything is either fought for (even when you look or think calmly) or run away from. Analyse yourself at a party you are either arguing, agreeing or fleeing.
Every single animal’s response is the same as yours. They differ only in their surroundings and their intelligence is reflected in how they cope their milieu. Fight or flight translates as “to eat or be eaten.”
Are your basic senses not developed for self preservation and propagation? So is the fish’s. They have the same basic senses as you: better and more adapted eyesight, hearing, touch, taste and smell.
Fish sense hunger, pain, and threat. They become aggressive when biological triggers signal the craving for food, or the need to defend a brood or a territory. Fish also communicate with one another. Fish can see colour and most strikingly collared species use their pigmentation to attract mates; or use colour to hide from and ward off predators. A fish can "hear" sound through the vibrations in the water, via a porous lateral line along the sides of its body and either goes to a feeding frenzy or flees along with the fearful fleeing that it hears happening nearby.
The sense of touch is highly developed and closely associated with their sense of taste, direction, self-preservation, and territoriality. Gouramis and Angelfish use their pelvic fins to taste and grope for food, but they also use their feelers as warning devices when coming out of a hiding place. They use their fins to feel their way around and to assert dominance during a territorial dispute. Catfish and most nocturnal species use their barbels to sense their way in the dark, as well as to taste their food.
A fish’s taste buds are located in receptors that are spread on several areas of the body. Many varieties of fish have nostrils with which to smell odour emanating from food and mating partners. These sensors help the fish taste and zero-in on the food. They also function as receptors for the "odour" that fish emit to denote position and rank within a community or territory. Most females also emit scents when they are ready to mate.
In an aquarium fish recognise the hands that feed them. Species, like the Oscar, Pacu, Grouper, Arowana, and Triggerfish express hunger by following the movements of their feeder. Peaceful fish that suddenly show aggressive behaviour towards tank mates and aquatic foliage may be signaling stress or insufficient feeding. Let’s take some examples of intelligence:
When a cuttlefish comes near its victim, it develops different bands of colour that flash on and off and hypnotize the victim, which is then caught.
The white striped Cleaner Shrimp sets up a shop in a cave in the reef for fish to come by and be cleaned of parasites. The fish will visit the shrimp on a regular basis. The shrimp gets fed; the fish gets relief from parasites.
Cleaner Fish remove parasites from the bodies of other fish. Sometimes when they accidentally bite their clients they apologise immediately by stroking their client's fins gently till the other fish calms down. Grouper fish bark to warn other fish when they see predators
The Puffer fish when threatened puffs up to twice its normal size by gulping water. Before mating the male Sun Fish digs a pit, which he cleans carefully and lines with aquatic plants. The female lays her eggs in the pit and both parents and even other Sunfish join together in protecting the nest till the eggs hatch and babies can take care of themselves.
The porcupine fish lives in the cracks of the coral reef. At night it moves along the bottom searching for the mollusc, which hides in the sand. The porcupine fish spurts tiny jets of water into the sand to uncover its prey.
Flatfish scrutinize their surroundings to work out the best disguise. A peacock flounder can mimic pebbles or sand with such perfection that it appears to vanish; put it on a chess-board and it will create a convincing black and white pattern on itself within seconds.
The Rockmover Wrasse are fish that work in pairs. They move stones often double their size to expose prey. One does the moving while the other eats the exposed food. Next time you eat a fish, remember you killed a being that lived and thought just the same as you.