Goldfish Feeder Fish - Live or let die?

I purchased a 13 cent goldfish feeder fish for my Crayfish & Dinosaur Senegal Bichir. While the other minnows & goldfish were consumed, this one healthy-nice looking goldfish survived & has grown up (now 2.5 inches) from the supplemental food I provide. I am wondering if I should raise him or let time take its toll with the Crayfish's Claws...Based on what I have heard (could be a fallacy), feeder fish are more prone to disease & are susceptible to horrible conditions when born leading to future problems. Please your professional opinion.