Not A Fish called Wanda but A Trout called Dooly (or Dooley) was really famous in Australia in the 1940s. He performed for the public at the Pemberton hatcheries in WA and needed to be nursed back to health after he was attacked by other trout. You can read about his fame in digitised newspapers on Trove. After his death in 1948, he was mummified in a plaque at the Pemberton hatcheries.
The State Library of New South Wales holds the journal called Tight Lines the journal of the NSW Rod Fishers’ Society, which also reported on his adventures. A government department asked us to locate the article about Dooly, which we found through looking through the issues of the print journal.