55 cards where the card types include “fish” or the text includes “fish”

Aboleth Spawn (Commander Legends: Battle for Baldur's Gate #662)
Ancient Carp (Dragons of Tarkir #44)
Aven Fisher (Dominaria Remastered #41)
Blufferfish (Unfinity #39)
Bounding Krasis (Magic Origins #212)
Breaching Hippocamp (Theros #43)
Bubble Smuggler (Murders at Karlov Manor #41)
Cloud Manta (Battle for Zendikar #71)
Coral Eel (Ninth Edition #S3)
Dandân (Time Spiral Timeshifted #19)
Deepglow Skate (Commander Masters #844)
Devouring Deep (Legends #50)
Electric Eel (The Dark #25)
Elusive Krasis (Gatecrash #160)
Exotic Pets (Streets of New Capenna #185)
Expendable Lackey (Streets of New Capenna #43)
Fleet Swallower (Ixalan #57)
Frost Fair Lure Fish (Doctor Who #129)
Grizzled Angler // Grisly Anglerfish (Eldritch Moon #63)
Grizzled Angler // Grisly Anglerfish (Eldritch Moon #63)
Gurmag Angler (Ultimate Masters #102)
Ichthyomorphosis (Theros Beyond Death #51)
Island Fish Jasconius (Fourth Edition #78)
Ithilien Kingfisher (The Lord of the Rings: Tales of Middle-earth #58)
Jace's Mindseeker (Duel Decks: Jace vs. Vraska #19)
Kapsho Kitefins (Magic 2015 #66)
Kingfisher (Urza's Destiny #36)
Kor Skyfisher (Modern Masters 2017 #11)
Manta Ray (Weatherlight #42)
Mer Man (Unsanctioned #25)
Moat Piranhas (Core Set 2020 #67)
Morska, Undersea Sleuth (Murders at Karlov Manor Commander #3)
Mystic Skyfish (Core Set 2021 #326)
Quagmire Lamprey (Mercadian Masques #154)
Quicksilver Fisher (Phyrexia: All Will Be One #66)
Red Herring (Murders at Karlov Manor #142)
Reef Worm (Commander 2021 #127)
Reservoir Kraken (Streets of New Capenna #56)
School of Piranha (Exodus #45)
Shipwreck Moray (Aether Revolt #45)
Skitter Eel (Ravnica: Clue Edition #98)
Sky-Eel School (Scars of Mirrodin #44)
Skyfisher Spider (The Brothers' War #221)
Skyreach Manta (Modern Masters 2015 #229)
Skyswimmer Koi (Kamigawa: Neon Dynasty #79)
Sleep with the Fishes (Streets of New Capenna #61)
Slipstream Eel (Commander Anthology Volume II #49)
Spiny Starfish (Masters Edition III #50)
Stinging Lionfish (Theros Beyond Death #69)
Surge Mare (Core Set 2019 #77)
Tidal Barracuda (Commander 2020 #39)
Vivid Flying Fish (Global Series Jiang Yanggu & Mu Yanling #4)
Wavebreak Hippocamp (Theros Beyond Death #80)
Windrider Eel (Archenemy: Nicol Bolas #30)
Wormfang Behemoth (Judgment #55)
Wormfang Manta (Judgment #58)

This search is finished. Now the real work can begin.