Below is a comprehensive list of everything in game that 'directly' affects your skill at catching fish.
You can see your current skill (if you have the pole) by checking your Other Accomplishments.
|A Real Head for Fish||Effect||10||50 turns||Item Loss, 2 Drunk||Level 6||Obtained from bottle of Fishhead 900-Day IPA|
|Astute Angler||Passive Skill||10||Always||None||Obtained from using Trout Fishing in Loathing, which is obtained from combats in The Haunted Library|
|Baited Hook||Effect||5||100 turns||Item Loss||None||Obtained from using wriggling worm|
|fishin' hat||Hat||5||While Equipped||None||Available in The Armory and Leggery (10k meat)|
|fishin' pole||Quest Item||20||Always||None||Obtained from visiting the Clan Floundry in your Clan VIP Lounge|
|Fishtacular Vernacular||Effect||10||40 turns||Item Loss, 1 Drunk||Level 3||Obtained from Bloody Nora|
|Floundering||Effect||5||40 turns||Item Loss, 1 Drunk||None||Obtained from low tide martini|
|government-issued slacks||Pants||5||While Equipped||None||Obtained by using 11 government requisition forms|
|High-Test Fishing Line||Effect||5||20 turns||Item Loss||None||Obtained from high-test fishing line (2500 meat)|
|Like a Fish to Walter||Effect||5||40 turns||Item Loss, 1 Fullness||Level 4||Obtained from Swedish massage fish|
|sonar fishfinder||Off-hand item||5||While Equipped||None||Obtained from combats in The Wreck of the Edgar Fitzsimmons|
|Pantogram pants||Pants||5||While Equipped||wriggling worm||None||iotm gives rental pants every day. sacrifice items for different bonuses. can choose a fishing bonus.|
|Video... Games?||Effect||5||5 Adventures||None||
|Item Loss, 1 Full||None||Obtained from bowl of Tastee-Wheet™|