Larsen is a prolific author of sport fishing books. Four of his books are on peacock bass, explaining their behaviors, habitats and the most effective techniques for catching them.
According to his website, Larsen's Outdoor Publishing, he has set seven peacock bass world line class records, including an all-tackle world record for the butterfly peacock bass (Cichla ocellaris). He also set a line class world record for Suwannee bass (Micropterus notius). In addition, he set two all-tackle world records for the following: the saber-tooth payara (Hydrolicus scomberoides); the tarpon snook (Centropomus pectinatus); and the South American silver croaker, also known as the freshwater corvina (Plagioscion squamosissimus).