Minnesota Fun Fish Facts 7:6-1 ! Minnesota Fun Fish Facts ©MN DNR, C. Iverson For more fun facts see the Nature Snapshots area of the Minnesota DNR website. Fish Are Fascinating! • A group of fish is called a school. • Most fish lack eyelids—although some saltwater • All fish are craniates, with skulls of bone sharks have a nictitating membrane that acts as or cartilage. an eyelid. • All fish are vertebrates (meaning that they have • It’s not always easy to tell the difference between backbones) and breathe through gills. a male fish and a female fish. In some species, • Most fish have fins and scales. males and females have different shapes or • Usually, fish are cold blooded, but several coloring; in other species there is no outwardly saltwater species, including some tuna and visible difference. sharks, maintain elevated body temperatures that • Fish skin has glands that secrete mucous that are substantially higher than surrounding waters. gives fish their sliminess and odor. Mucous • There are more than 27,000 living species of fish covers wounds to prevent infection, and protects worldwide. Approximately 20,000 of these are fish from bacterial infections from fungus, mold, bony fish. and other parasites. The slime covering also • Fish are the largest population of vertebrates. makes it easier for fish to slide through water There are more fish than all mammals, reptiles, and keeps scales lubricated. amphibians, and birds combined. Although • The muscle mass of most fish is segmented into fish species are numerous, several groups of zig-zaged shapes called myotomes. These muscle invertebrates far outnumber fishes. Nematodes, segments help fish move through the water. or roundworms, are the most abundant, with When you eat a fish, the meat is the muscle that as many as one million estimated species. folds or peels off in layers. Approximately 20,000 species of nematodes • The streamlined shape of a fish’s body enables it have been described. One million insect species to easily cut through water as it swims. have been identified, so they, too, outnumber • An esophagus, the tube between the mouth and fishes. There are approximately 55,000 species of stomach, is flexible. A fish esophagus usually crustaceans, including lobsters, crabs, shrimps, can handle anything that fits into the fish’s and barnacles. mouth. It can even adjust mid-swallow—just in © 2010 Minnesota DNR • MinnAqua • USFWS Sport Fish Restoration 7:6-2 Minnesota Fun Fish Facts case the fish eats something that happens to be Minnesota Fish Family Trivia tail fins. Catfish bodies are covered with taste buds considerably larger than itself. instead of scales. These many taste buds—and the • A fish’s food slides through the esophagus into In 2006, Minnesota was home to 160 species of barbels—help catfish locate food. the stomach. From the stomach, food moves to fishes, 141 of them native. The number of species the intestines where digestion continues. Fish increases as new non-native species inextricably Catfish intestines are lined with mucous that moves establish themselves in Minnesota waters. There are • The two large species of catfish commonly found digesting food, and aids in the absorption 26 families of Minnesota fishes. Here are some facts in Minnesota are channel catfish and flathead of protein. The kidney, liver, and gall bladder about some familiar fish families as well as some of catfish. contribute enzymes and acids that further the unusual fish families that live in Minnesota. • Catfish barbels aren’t “stingers” and won’t sting process the food. After needed protein, fat, and you. They’re an organ that senses taste, touch, carbohydrates have been extracted from the food The Bowfin Family (Amiidae) and smell. But these fish do have sharp spines and absorbed, the waste passes through the fish's with poison glands—one in the leading edge vent, or anus. of their top (dorsal) and one in each of their • In order to be buoyant, and to expend as little side (pectoral) fins. If you’re not careful when energy as possible, most fish have an air (or gas) handling these fish, you can poke your hand on bladder to regulate buoyancy in the water. The air these spines. bladder inflates and deflates to keep the fish from sinking like a stone or bobbing to the surface. • Bowfin are the last surviving members of a Bullheads Adjusting the volume of gas in the air bladder formerly large family of fish—the rest exist only • Minnesota has three species of bullheads: brown, brings the fish’s overall density close to the density as fossilized remains. black, and yellow. of the surrounding water. This gives the fish the • The name refers to the long, undulating dorsal • Bullheads have as many as 100,000 taste buds ability to hover at a particular level in the water. fin along the back of these fish. scattered over their bodies. Many taste buds are Hagfish, lampreys, sharks, rays, and chimeras don’t • Bowfin come to the surface every few minutes to also found on their barbels. Scientists think that have gas bladders. There are also several species breathe air, using their swim bladder like a lung. well-developed sensory abilities help bullheads of ray-finned fishes that don’t have gas bladders, They also use gills to breathe in water. They can find food in muddy, dark water. including some Minnesota species. survive out of water for a considerable length of • Black bullheads are extremely hardy and do • A fish’s brain is located at the end of the time. A farmer once found a live bowfin in moist well in aquaria, so they’re often used in vertebral column that runs through its body. The soil while plowing a field that had been flooded a scientific studies. spinal cord inside the column transmits messages few weeks earlier. from various parts of the body to the brain • The male bowfin turns dark green while The Codfish or Cuskfish Family (Lotidae) and vice versa. The sections of the brain are the spawning and guarding its young. forebrain, ’tween brain, midbrain, and hindbrain, • In recent years, aquaculturists have shown all of which are protected by a skull. interest in harvesting bowfin eggs for caviar. • Fish breathe by taking water in through their • Bowfin are also known as dogfish. mouths and pushing it over the surface of their gills. The gills are protected by structures called The Catfish Family (Ictaluridae) Burbot gill rakers. • Most codfishes live in oceans. The only • The fish’s inner ear includes an ear stone freshwater species in this family is the burbot. (otolith). Sound signals are transmitted to the • In Minnesota, burbot are commonly known brain after the sound registers in the ear stone. as eelpout. Eelpout is the name of a family of Otoliths grow each year, adding rings similar saltwater fishes (Zoarcidae), but burbot are called to the growth rings of a tree. Fish biologists eelpout simply because they resemble these examine the annual rings of the otolith to Catfish exist throughout the world, but the fishes. Their Latin name, Lota lota, comes from determine the ages of some types of fish. Ray- Ictaluridae family lives only in North America. the French word for codfish. It’s possible that finned fishes have three otoliths and lobe-finned There are nine catfish species in Minnesota: three the word burbot is derived from bourbe, a French fishes have two. Paddlefish and sturgeon (like catfish species, three types of bullheads, and three word meaning mud from a pond or lake. sharks, rays, and chimeras) don’t have otoliths. smaller fish species. All members of this family have • Burbot have a single barbel located under • Fish scales are laid down in rings each year (like whisker-like barbels around their mouths and an the chin. tree rings) and can be used to age fish. adipose fin on their back between the dorsal and • Burbot are the first fish to spawn each year. They © 2010 Minnesota DNR • MinnAqua • USFWS Sport Fish Restoration Minnesota Fun Fish Facts 7:6-3 tail fins. Catfish bodies are covered with taste buds spawn in the middle of winter. They’re the only instead of scales. These many taste buds—and the fish in Minnesota to spawn under the ice. barbels—help catfish locate food. • In early February, an annual International Eelpout Festival on Leech Lake includes a Catfish black-tie dinner on the lake, ice bowling, and a • The two large species of catfish commonly found fishing tournament. The angler who catches the in Minnesota are channel catfish and flathead biggest burbot wins a seven-foot-tall trophy. catfish. • Catfish barbels aren’t “stingers” and won’t sting The Drum Family (Sciaenidae) you. They’re an organ that senses taste, touch, and smell. But these fish do have sharp spines with poison glands—one in the leading edge of their top (dorsal) and one in each of their side (pectoral) fins. If you’re not careful when handling these fish, you can poke your hand on these spines. Bullheads The freshwater drum is the only species of the large • Minnesota has three species of bullheads: brown, family of drum fishes that lives in Minnesota—and black, and yellow. it’s the only freshwater member of the drum family. • Bullheads have as many as 100,000 taste buds scattered over their bodies. Many taste buds are Freshwater Drum also found on their barbels. Scientists think that • Freshwater drum are also known as sheepshead well-developed sensory abilities help bullheads or croakers. It’s the only freshwater fish with a find food in muddy, dark water. lateral line that extends all the way to the end of • Black bullheads are extremely hardy and do its tail fin.