retold by Richard L. Dieterle
Version 1. There once lived in Lake Winnebago a giant fish, which most believe to have been a sturgeon. There was one part of the lake that herds of moose, elk, and deer liked to swim across in their migrations. The fish would wait until they were in the deeper water, then attack them by dragging them under the waves and swallowing them whole. Nobody would paddle his canoe into the area for fear that he and his boat would fall victim to the same fate.
The hunting of cervids by this fish went on for years, until one day some hunters found the fish floating dead in the water near the shore. It soon became apparent what had killed him: when they examined his underside, they found elk horns protruding through his flesh. He had swallowed a huge elk whole, but could not digest its massive horns.
Even today, it is said, some of the descendants of this fish live in Lake Winnebago. 
Version 2. One day a large herd of long legged elk were midway across a stream when a single fish came along and swallowed the entire herd at once. 
Commentary. Most stories like this are told of Waterspirits (see The Waterspirit of Rock River). A very similar account is given as early as 1766-1768 by Capt. Jonathan Carver of the British Army who says,
The Winnebago Lake is about fifteen miles long from eaſt to weſt, and six miles wide. At its south-eaſt corner, a river falls into it that takes its rise near ſome of the northern branchs of the Illinois River. This I called the Crocodile River, in conſequence of a ſtory that prevails among the Indians, of their having deſtroyed, in ſome part of it, an animal, which from their deſcription muſt be a crocodile or an alligator. 
Inasmuch as alligators do not live that far north, it is rather more likely that Carver has euhemerized a legend about the killing or sacrifice of a Waterspirit.
Links: Fish Spirits, Lake Winnebago.
Stories: featuring (spirit) fish as characters: The Man who went to the Upper and Lower Worlds, The Were-Fish, The Greedy Woman, Wolves and Humans, River Child and the Waterspirit of Devil's Lake, The Spirit of Maple Bluff, Lake Wąkšikhomįgra (Mendota): the Origin of Its Name, The King Bird, Fish Clan Origins, The Blessing of a Bear Clansman, Trickster's Adventures in the Ocean, Otter Comes to the Medicine Rite, Hare Visits the Bodiless Heads; featuring sturgeons as characters: Redhorn's Father, River Child and the Waterspirit of Devil's Lake, Wolves and Humans, The Twin Sisters, see also White Flower; mentioning elks: Elk Clan Origin Myth, The Animal who would Eat Men (v. 1), The Elk's Skull, Hare Recruits Game Animals for Humans, Deer Clan Origin Myth, The Creation Council, Hočąk Clans Origin Myth, Spear Shaft and Lacrosse, Buffalo Clan Origin Myth, Origin of the Hočąk Chief, Little Fox and the Ghost (v. 2); See The Girl who Refused a Blessing from the Wood Spirits; set at Lake Winnebago (Te Xete): Lake Winnebago Origin Myth, The First Fox and Sauk War, White Thunder's Warpath, Traveler and the Thunderbird War (v. 2), The Wild Rose, The Two Boys, Great Walker's Warpath, The Blessing of a Bear Clansman, The Fox-Hočąk War, Holy Song, First Contact (v. 2), The Two Children (?).
Themes: an aquatic creature eats cervids whole: The Waterspirit of Rock River; being swallowed whole: The Hill that Devoured Men and Animals, Hare Gets Swallowed, The Waterspirit of Rock River, The Baldheaded Warclub Origin Myth, The Bungling Host, The Dipper.
Map: Lake Winnebago.
 Charles E. Brown, Wisconsin Indian Place Legends (Madison: Works Progress Administration, 1936) 10. Dorothy Moulding Brown, Wisconsin Indian Place-Name Legends, Wisconsin Folklore Booklets (Madison: 1947) 9.
 Paul Radin, "Short Tales," Winnebago Notebooks, Winnebago IV, No. 7i(Philadelphia: American Philosophical Society) #18, "The Elk Crossing the Stream."
 Captain Jonathan Carver, Travels through the Interior Parts of North America, in the Years 1766, 1767, and 1768 (Minneapolis: Ross & Haines, 1956 ) 37.