I know a Youtuber who has a pond (Well over 20,000 gallons, he uses as duck pond for his MANY ducks) with Mayan Cichlids, Tilapia, and Midas Cichlids, which they feed to Oscars, Gar, Redtail Catfish, Shovelnose Catfish, Pacu, Arowana's, and other predatory fish. He casts cast nets out to get tilapia and other cichlids in his pond. His food source to his predatory fish is the baby fish he has in the pond. If your interested, his channel is called Paul Cuffaro. Also, make sure Tilapia are legal in your area because Blue Tilapia and most species of Tilapia are Illegal in California.