Photo / Alan Gibson. The IGFA maintains the World Records for all species of game fish. The result is a rainbow trout that averages 3 to 8 pounds in size, with double-digit fish refreshingly frequent, and fish in the low- to mid-20-pound ranges a real possibility almost every day on the lake. The fish weighed 48 lb (22 kg) and was a genetically modified hatchery escapee. Their image as a selective eater is only a legend. Rainbow trout are predators with a varied diet, and will eat nearly anything they can grab. Rainbows are not quite as piscivorous or aggressive as brown trout or lake trout (char). Aussie angler Frank Bluch is no stranger to light line records. Fishing for brown trout. 19 Jan, 2019 04:00 PM 4 minutes to read. The previous world record was held by Sean's twin brother Adam, who pulled a 43-pound, 10-ounce rainbow trout from Lake Diefenbaker in 2007. You can search all IGFA World Records for freshwater and saltwater fishes in All-TackleLine Class, All-Tackle Length for male, female and junior anglers. The species (Oncohynchus mykiss) was originally named by Johann Julius Walbaum in 1792 based on type specimens from Kamchatka. The International Game Fish Association recognizes the world record for rainbow trout as a fish caught on Saskatchewan's Lake Diefenbaker by Sean Konrad on September 5, 2009. Rainbow trout are a popular target for fly fishers, and several angling methods are used. Angler who caught world-record brown trout says he will produce proof if he's left alone . The world-record Kamloops was a 37-pound fish, surprisingly caught here and not at its native Lake Kootenay. Posted: Jul 19, 2017 7:23 PM PT | Last Updated: July 20, 2017. It was originally thought to be a rainbow trout. Mark Adams, of Pocatello, caught this 34-pound, 11-ounce cutbow hybrid trout in the American Falls Reservoir July 25. He recently caught this 13.3-kilogram (29-pound, 5-ounce) rainbow trout to set the new IGFA Men’s 2-kg (4-lb) Tippet Class World Record.