News Animals Fish Are Much Smarter Than You Think By Katherine Martinko Katherine Martinko Twitter Senior Editor University of Toronto Katherine Martinko is an expert in sustainable living. She holds a degree in English Literature and History from the University of Toronto. Learn about our editorial process Updated October 11, 2018 This story is part of Treehugger's news archive. Learn more about our news archiving process or read our latest news. CC BY 2.0. insunlight Share Twitter Pinterest Email News Environment Business & Policy Science Animals Home & Design Current Events Treehugger Voices News Archive Science has shown fish to be capable of collaboration, recognition, astonishing feats of memorization, and craving physical touch. Fish are usually not considered to be the most intelligent animals. They have long been viewed as simple creatures that spend their lives swimming around a vast shadowy world about which we understand relatively little. They are caught relentlessly – an estimated half-trillion a year that, if lined up end-to-end, would reach the sun – and are either eaten or tossed back into the ocean as unwanted bycatch. Scientists, however, are beginning to understand more about these creatures, particularly that they are far more remarkable than previously thought. In fact, new discoveries about the intelligence of fish make our human attitude toward fish seem completely outdated and unfair, not to mention cruel. In a New York Times article titled, “Fishes Have Feelings, Too,” Jonathan Balcombe, author and director of animal sentience at the Humane Society Institute for Science and Policy, describes several fascinating examples of fish exhibiting astonishing intelligence. One example is the frillfin goby, a five-inch-long fish with prominent eyes, puffy cheeks, and a pouty mouth. Frillfins hide in shallow rocky pools at low tide and, if they sense danger, jump into nearby pools with excellent accuracy. How do they manage to avoid getting stranded on rocks? “A series of captive experiments dating from the 1940s found something remarkable. They memorize the tide pool layout while swimming over it at high tide. They can do it in one try, and remember it 40 days later. So much for a fish’s mythic three-second memory.” Balcombe also describes tool use by fish. The orange-spotted tusk fish uncovers a clam, carries it in its mouth to a rock, and smashes it open with a series of deft head flicks: “This is more than tool use. By using a logical sequence of behaviors, involving several distinct stages, the tusk fish also shows itself to be a planner.” Some fish even seek out physical touch, approaching divers for belly and face rubs. One experiment found that sturgeon in a stressful situation (covered by a minimal amount of water) sought caresses from a mechanical model of a cleaner-fish, which consequently lowered the sturgeon’s blood pressure significantly. In other situations, fish that are waiting to be cleaned observe how well a cleaner fish does its job before choosing which one to use. Those same cleaner fish have been shown to work better under pressure, with an audience observing. Fish are even capable of collaboration while hunting, sharing the prey afterward, and of individual recognition, i.e. a particular grouper fish and moray eel who know each other and have worked together to hunt in the past. Balcombe paints a convincing picture of an underwater world that is far more complex than we humans realize. If fish are truly this intelligent, then the thought of eating fish becomes a whole lot more uncomfortable, particularly when you think of the suffering endured by these animals when they are crushed in nets or suffocated on board boats, not to mention to the effect on plummeting fish populations due to overfishing. "We have driven many charismatic mammalian species to a point where they’re in peril of extinction. And so it is with many magnificent fish species like cod, swordfish, the Atlantic halibut and the scalloped hammerhead shark."Since 1960, populations of bluefin tunas — massive, warm-blooded group hunters that can swim up to 50 miles per hour — have declined by 85 percent in the Atlantic and 96 percent in the Pacific. That’s the story behind the convenient rows of canned tuna at the store." It's better, perhaps, to keep these remarkable animals as food for thought.