I used to keep a pacue when i was a kid, and i had one goldfish that i bought as a feeder, and he just happened to survive for a year and half, and got quite large. He was just too quick for the pacu, i called him Uber, as he was the superior fish, darwinism at work, then one day, in a mad dash aways from the pacu, he jumped out, and i came in to find him stunned on the ground, threw him back in, and he was too slow, the pacu nailed him...... if any of my fish are fast enought to escape my oscar and flowerhorns, they can gladly live.