How Long Was The Biggest Fish Ever Caught?
How Long Was The Biggest Fish Ever Caught? The biggest fish ever known to have lived is a specimen of the marine fossil species Leedsichthys problematicus. Dating back some 165 million years, it is estimated to have reached around 55 ft (16.76 m) in length. How long was the biggest fish ever? Enter Leedsichthys problematicus.