Meaning

noun flesh of scaleless food fish of the southern United States; often farmed

noun large ferocious northern deep-sea food fishes with strong teeth and no pelvic fins

noun any of numerous mostly freshwater bottom-living fishes of Eurasia and North America with barbels like whiskers around the mouth

originFrom cat + fish. Likely so named for its prominent barbels like a cat's whiskers. Compare West Frisian katfisk (“catfish”), Dutch katvis (“catfish”). Compare also German Seekatze (“catfish”, literally “sea-cat”).

Etymology from Wiktionary, CC BY-SA 3.0